Kiara asked in Science & MathematicsMathematics · 9 years ago

# How do you add/ subtract fractions?

1/2 + 3/10 = ____

(Please put the answer in a fraction & in its lowest terms)

& Explain to me how you do the problem.

Subtracting Example:

2/3 - 1/2 = ___

(Please put you the answer in a fraction & in it's lowest term)

And explain to me how you did it.

Relevance
• TrueID
Lv 4
9 years ago

You need to find the common denominator ( the bottem part of the fraction needs to match)

So you have 1/2, and 3/10, [since 2 does not match 10]

Multiply 1/2 by 5 (both top and bottem must be multiplied when doing this)

After multiplying the fraction 1/2 by 5, you get

so 5/10 + 3/10 = 8/10

To find the lowest terms, ask yourself what you number can both 8 and 10 be divided by

you can divided 8 by 2, and you can also divide 10 by 2

2) When dealing with Odd and Even denominator, just multiply the denominator of each other

(2/3) multiply by 2 both bottem and top

(1/2) multiply by 3 both bottem and top

you get 4/6 - 3/6 = 1/6

• 4 years ago

a million) 5/8 - a million/4= 5/8-2/8=3/8 2) 5/6 - a million/3= 5/6-2/6=3/6=a million/2 3) 3/4 - a million/3= 3*3/12-a million*4/12=9/12-4/12=5/12 4) 5/12 - 2/12=3/12=a million/4 5) 7/10 - a million/15= 7*3/30-a million*2/30=21/30-2/30=19/30 u might desire to discover on the backside of the "new" fraction the smaller sort which would be divided via the two the bottoms of the two (or greater) fractions that u upload or subtract, as u c, case in point, interior the num 3 the smaller num "obtainable" is 12 so 12 (the backside of the fraction u might have) / 4(the backside of the 1st fraction)=3 that u moltiply with the three that u already have 3*3/12=9/12 in certainty 9/12 is an identical element than 3/4... than u do an identical element with the different fraction so as that u could have 2 fraction with an identical backside that u can basically subtract or upload.

• 9 years ago

first find LCD (lease common denominator) whether its add/subtract

first fraction has a denom of 2 & second has a denom of 10

2 has factors of 1 & 2

10 has factors of 1, 2 & 5

the least common factors of both is 1, 2 & 5

their least common denominator is the multiplication of 1, 2 & 5 = 10

What is missing for the LCD of the first fraction? 1 & 2...needs 5

What is missing for the LCD of the second fraction? 1, 2 & 5...needs nothing

Okay remember in grade school the multiplication tables, specifically ones "1"

where 1 times any number is still that number? no change! 1*1 = 1, 1*2 = 2, and so on

Okay 5 was missing from the first fractions denom...so multiply it by 5, but whatever we

do to the denom of that fraction must also be done to its numerator, ie multiply it also by 5 which would be reduced 5/5 = 1 which is legit 1*half = half

5*1/(5*2) + 3/10 = 5/10 + 3/10

now that we have the same denominator we have

(5 + 3)/10 = 8/10

not in lowest terms, reduce to 4/5

LCD = 6

2/3 - 1/2 = 2*2/(2*3) - 3*1/(3*2) = 4/6 - 3/6 = (4 - 3)/6 = 1/6

• Anonymous
9 years ago

for adding you make the denominator the same.

ex:

1/2 + 3/10

1/2 = 5/10

then:

5/10+3/10= 8/10

simplify:

8/10=4/5