8 - (2a+7) = a+40 I need to know this I'm havin a lot of trouble figuring it out

8 - (2a + 7) = a + 40 Distribute/multiply - into (2a + 7)

8 - 2a - 7 = a + 40

1 - 2a = a + 40 Add 2a on both sides

1 = 3a + 40 Subtract 40 on both sides

-39 = 3a Divide 3 on both sides

-13 = a

[proof]

8 - (2a + 7) = a + 40

8 - (2 (-13) + 7) = - 13 + 40

8 - (-26 + 7) = 27

8 - (-19) = 27

8 + 19 = 27

27 = 27

Simplify brackets

8 - 2a - 7 = a + 40

Simplify 8 - 2a - 7 to - 2a + 1

-2a + 1 = a + 40

Add 2a to both sides

1 = a + 40 + 2a

Simplify a + 40 + 2a to 3a + 40

1 = 3a + 40

Subtract 40 from both sides

1 - 40 = 3a

Simplify 1 - 40 o - 39

-39 = 3a

Divide both sides by 3

-39/3 = a

Simplify 39/3 to 13

-13 = a

Switch sides

a = - 13