9(y-5)+6(y+1)=21

Solution for 9(y-5)+6(y+1)=21 equation:

Simplifying
9(y + -5) + 6(y + 1) = 21

Reorder the terms:
9(-5 + y) + 6(y + 1) = 21
(-5 * 9 + y * 9) + 6(y + 1) = 21
(-45 + 9y) + 6(y + 1) = 21

Reorder the terms:
-45 + 9y + 6(1 + y) = 21
-45 + 9y + (1 * 6 + y * 6) = 21
-45 + 9y + (6 + 6y) = 21

Reorder the terms:
-45 + 6 + 9y + 6y = 21

Combine like terms: -45 + 6 = -39
-39 + 9y + 6y = 21

Combine like terms: 9y + 6y = 15y
-39 + 15y = 21

Solving
-39 + 15y = 21

Solving for variable 'y'.

Move all terms containing y to the left, all other terms to the right.

Add '39' to each side of the equation.
-39 + 39 + 15y = 21 + 39

Combine like terms: -39 + 39 = 0
0 + 15y = 21 + 39
15y = 21 + 39

Combine like terms: 21 + 39 = 60
15y = 60

Divide each side by '15'.
y = 4

Simplifying
y = 4