Solve each equation.
7) 18 =-2+a
8) -7= m - 12
9) -8(7 + 7n)=-336
10) -140=-7(-4+36)

7) a= 20

8) m= 5

9)n = 5

10) b = 8

Step-by-step explanation:

7) 18+2=-2+2+a

>> 20 = a >> a = 20

18 + 2 = 20 so that isolates the variable leaving a = 20

8) -7+12 = m -12+12

>>> 5 = m >> m = 5

-7 + 12 = 5 so that again isolates the variable leaving m = 5

9) -8(7 + 7n) = -336

>> -56+56 + -56n = -336+56

>>> -56n/-56 = -280/-56

>>>> n = 5

use distributive property, cancel out necessary numbers, isolate the variable. leaving n = 5.

10) -140 = -7(-4 + 3b)

>>  -140 = 28 - 21b >> -140-28 = -21b +28-28 ( flipped the numbers)

>>>  -168/-21 = -21b /-21

>>>> 8 = b >> b =8

Hope it helps!