# MATH EQUATIONS HELP!!?

Hi! I'm having trouble with these three math equations. I've done them all a few times, but I can't seem to get them right. Will somebody please help me? I'll choose best answer!

1. 6(14 - 3x) +20x=90

2. 2/3x +15 = 1/2x +4

3. 2.9n + 1.7 = 3.5 + 2.3n

Thanks! :D

Relevance

1.

6(14 - 3x) +20x=90

84-18x+20x = 90

84+2x = 90

(84+2x)-84 = 90-84

84+2x-84 = 6

84-84+2x = 6

2x = 6

(2x)/2 = 6/2

x = 3

2.

2/3x +15 = 1/2x +4

I assume that you mean

(2/3)x +15 = (1/2)x +4

[(2/3)x +15]-(1/2)x-15 = [(1/2)x+4]-(1/2)x-15

(2/3)x-(1/2)x = -11

(2/3)x*6-(1/2)x*6 = -11*6

4x-3x = -66

x = -66

3.

2.9n + 1.7 = 3.5 + 2.3n

(2.9n+1.7)-2.3n-1.7 = (3.5+2.3n)-2.3n-1.7

2.9n-2.3n+1.7-1.7 = 2.3n-2.3n+3.5-1.7

0.6n = 1.8

(0.6n)/0.6 = 1.8/0.6

n = 1.8/0.6

n = (1.8*10)/(0.6*10)

n = 18/6

n = 3

HOPE THIS HELPS.

• Login to reply the answers
• 1. 6(14 - 3x) +20x=90

6*14 - 6*3x + 20x = 90, distributive property

84 - 18x + 20x = 90

84 + 2x = 90, combine like terms

2x = 6, additive inverse on both sides

x = 3, divide by 2

2. 2/3x +15 = 1/2x +4

2/3x - 1/2x + 15 = 1/2x - 1/2x + 4

2/3x - 1/2x + 15 = 4

2/3x - 1/2x + 15 - 15 = 4 - 15

2/3x - 1/2x = -11

4/6x - 3/6x = -11, common denominator

1/6x = -11

x = -11 * 6 = -66

3. 2.9n + 1.7 = 3.5 + 2.3n

29n + 17 = 35 + 23n, multiplied entire equation by 10

29n - 23n + 17 = 35 + 23n - 23n

29n - 23n + 17 = 35

29n - 23n + 17 - 17 = 35 - 17

29n - 23n = 35 - 17

6n = 18

n = 3

• Login to reply the answers
• 1) 84 - 18x+20x = 90

-18x+20x = 90-84

2x = 6

x= 6/2

x=3

2) 2/3x-1/2x= 4-15

1/6x = -11

x= -66

3) 2.9n -2.3n = 3.5 - 1.7

0.6n = 1.8

n = 3

• Login to reply the answers
• 1. Distribute the 6, so you get 84 - 18x + 20x = 90

then combine like terms -18x + 20x = 90 - 84

so 2x = 6

and x = 3

2. Multiply everything by 6, so you get 4x + 90 = 3x + 24

then combine like terms so you have 4x - 3x = 24 - 90

so x = -66

3. Combine like terms: 2.9n - 2.3n = 3.5 - 1.7

.6n = 1.8

n = 3

• Login to reply the answers
• 1]

6*14-6*3x+20x=84-18x+20x=90

this implies 2x=90-84=6

this in turn implies 2x=6

hence x=6\2=3

therefore x=3

2]

2\3x+15=1\2x+4

shifting places n getting all "x"terms on one side of the equation we get

2\3x-1\2x=4-15

take lcm of 3x and 2x

it is 6x

so 4-3\6x=-11

1\6x=11

6x=1\11

x=1\11*6

x=1\66

3]

2.9n-2.3n=3.5-1.7{this we got after shifting places on either side of equal to sign}

after that

0.2n=2.5

n=2.5\0.2

hence n=12.5

that's it dude,did you get me,the answers are correct

• Login to reply the answers
• 6(14 - 3x) + 20x = 90

84 -18x +20x = 90 # subtract 84

2x = 6

x = 3

---

2/3x +15 = 1/2x +4 # multiply with 6

4x + 90 = 3x + 24 # subtract 3x, subtract 90

x = -66

---

2.9n + 1.7 = 3.5 + 2.3n # subtract 2.3n, subtract 1.7

0.6n = 1.8

n = 3

• Login to reply the answers
• 1. 84-18x+20x=90

84+2x=90

2x=6

x=3

2. 4x+90=3x+24

x+90=24

x= -66

3. 2.6n=1.8

n=0.69 (sorry i dont think this one is right though)

• Login to reply the answers
• 84-18x+20x=90

2x+84-84=90-84

2x=6 x=3

2/3x+15=1/2x+4

3x+90=3x+24

x=-66

2.9n+1.7= 3.5+2.3n

.6n=1.8

n=3

• Login to reply the answers
• Anonymous

1.

6(14-3x)+20x=90

84-18x+20x=90

-18x+20x=6

2x=6

x= 3

2.

2/3x+15=1/2x+4

2/3x-1/2x=4-15

1/6x=-11

x= -66

3.

2.9n + 1.7 = 3.5 + 2.3n

2.9n-2.3n=3.5-1.7

.6n=1.8

n = 3

• Login to reply the answers
• 1. x=3

2. x=-66

3. n=3

Source(s): this is easy 7th grade algebra.... and my current math teacher is the bomb!
• Login to reply the answers