7. 9 - (5-7y) = 13+4y

12. 5 (3m+4) = 3 (4m+7)

14. 5 (a+2) - 3 (3a-5) = 1

17. 5 (v+2) + 3 (v-5) = 19

Step-by-step explanation:

7) 9 - (5 - 7y) = 13 + 4y

9 - 5 + 7y = 13 + 4y

4 + 7y = 13 + 4y

7y = 13 + 4y - 4

7y - 4y = 13 - 4

3y = 9 {divide both side by 3}

y = 9/3

y = 3

12) 5 (3m+4) = 3 (4m+7)

5*3m + 5*4 = 3*4m + 3*7

15m + 20 = 12m + 21

15m = 12m + 21 - 20

15m - 12m = 21 - 20

3m = 1

m = 1/3

14) 5 (a+2) - 3 (3a-5) = 1

5*a + 5*2 + (-3) * 3a - 5 * (-3) = 1

5a + 10 - 9a + 15 = 1

5a - 9a + 10 + 15 = 1

-4a + 25 = 1

-4a = 1 - 25

-4a = - 24

a = - 24/-4

a = 6

17) 5 (v+2) + 3 (v-5) = 19

5*v + 5*2 + 3*v - 5 * 3 = 19

5v + 10 + 3v - 15 = 19

5v + 3v + 10 - 15 = 19

8v - 5 = 19

8v = 19 + 5

8v = 24

v = 24/8

v = 3