Anonymous

# Help on Math show all work?

8. 12k + 7 = 31..i know k=2 but i just don't know how to show the work for it

9. 13n + 42 = 81..i know n= 3 but i just don't know how to show the work for it

10. 56 = 17p - 29

11. w/4 - 21 = -3

Update:

Relevance
• Anonymous

8.

12k = 31 - 7

12k = 24

k = 24 / 12

k = 2

9.

13n + 42 = 81

13n = 81 - 42

13n = 39

n = 39 / 13

n = 3

10.

56 = 17p - 29

56 + 29 = 17p

85 = 17p

p = 85 / 17

p = 5

11.

w/4 - 21 = -3

w / 4 = -3 + 21

w / 4 = 18

w = 18 x 4

w = 72

One question: how did you know the answers to 8 and 9 if you didnt know how to get to those answers?

8. 12k + 7 = 31

12k = 31 - 7

12k = 24

k = 2

9. 13n + 42 = 81

13n = 81 - 42

13n = 39

n = 3

10. 56 = 17p - 29

17p = 85

p = 5

11. w/4 - 21 = -3

w - 84 = -12

w = 72

• Anonymous

12k plus 7 = 31

Minus seven to get rid of it and minus seven on the other side.

so 31 minus 7

Then once you have the answer. Divide 12 by 12 and the same to the 31 minus 7 answer.

What ever you do on one side, you to do the other. Opposite of the integer sign also. So if it's 2k plus 7 you minus seven to get rid of it and minus seven on the other side.

8. 12k + 7 = 31

12k = 31 - 7

12k = 24

k = 2

9. 13n + 42 = 81

13n = 81 - 42

13n = 39

n = 3

10. 56 = 17p - 29

17p = 85

p = 5

11. w/4 - 21 = -3

w - 84 = -12

w = 72

Do the same for all of them. Good Luck!

Yep here you go.....hope this helps

8. 12k + 7 = 31

12k = 31-7

12k = 24

12k/12 = 24/12

k = 2

9. is the same way

10. is the same as 8 and 9

11. w/4 - 21 = -3

w/4 = -3 + 21

w/4 = 18

w/4 *(4) = 18 * (4)

w = 72

12k + 7 = 31

-7 -7

12k=24

12k/12=24/12=2

13n+42=81

-42 -42

13n/13=39/13= 3

56=17p-29

+29 +29

85=17p

85/17=17p/17

=5

and I'm not sure on the last one.

place all the numbers to the right of the equal sign, if a number crosses the equal sign, change the sign and then add:

12k + 7 = 31

12k = 31 - 7

12k = 24

k = 24/12

k = 2

• Anonymous

12k+7=31

12k=31-7

12k=24

k=24/12 (the '/' means divided by)

k=2

there ya go! your just simply swaping sides with everything.. heres another..

sorry i dnt have enough time to do them all.. hopefully you get the idea

13n+42=81

13n=81-42

13n=39

n=39/13

n=3

12(2) + 7 = 31

24+7=31

31=31

13(3) + 42 = 81

39 + 42 = 81

81=81

17p - 29 = 56

------ ------

17 17

+-29 +-29

--------------------

p = -25.7 ???

w

--- - 21 = -3

4

(4)w

------- -21 = -3 (4)

w -12

W - 21 = -12

+-21 +-21

---------------------

W = -33

Hope i helped. good luck. :D

Source(s): Pre- Alg. :D
• Anonymous
5 years ago

42= c+(c+8) 42= 2c+8 34=2c 17=c <there's the shorter call now add 8 for the longer call 17+8=25 and to check we add 17 to 25 and get 42, the total the phone bill said we had talked