Question

Solve for the equation 3y+4x=9 for y

Answer 1

3y + 4x = 9 (equation)

3y = -4x + 9 (subtract 4x on both sides to get (y) to one side)

y = -4/3x + 9/3 (divide both sides by three to get (y) alone)

y = -4/3x + 3 (simplify)

that's your answer :)

Answer 2

simplifying:
3y=4x+-9

reorder the terms:
3y=-9+4x

solving 
3y=-9+4x

solving for variable 'y'

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

divide each side by '3'
y=-3+1.333333333x

simplifying 
y=-3+1.333333333x