3(y-4)+9(y+1)=45

Solution for 3(y-4)+9(y+1)=45 equation:

Simplifying
3(y + -4) + 9(y + 1) = 45

Reorder the terms:
3(-4 + y) + 9(y + 1) = 45
(-4 * 3 + y * 3) + 9(y + 1) = 45
(-12 + 3y) + 9(y + 1) = 45

Reorder the terms:
-12 + 3y + 9(1 + y) = 45
-12 + 3y + (1 * 9 + y * 9) = 45
-12 + 3y + (9 + 9y) = 45

Reorder the terms:
-12 + 9 + 3y + 9y = 45

Combine like terms: -12 + 9 = -3
-3 + 3y + 9y = 45

Combine like terms: 3y + 9y = 12y
-3 + 12y = 45

Solving
-3 + 12y = 45

Solving for variable 'y'.

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

Add '3' to each side of the equation.
-3 + 3 + 12y = 45 + 3

Combine like terms: -3 + 3 = 0
0 + 12y = 45 + 3
12y = 45 + 3

Combine like terms: 45 + 3 = 48
12y = 48

Divide each side by '12'.
y = 4

Simplifying
y = 4