The point $(a, b)$ lies on the line with the equation $3x + 2y = 12.$ When $a = 4$, what is the value of $b$?

"a" = x = 4

So

3(4) + 2y = 12

12 + 2y = 12 subtract 12 from both sides

2y = 0 divide by 2 on both sides

y = 0 = " b "

Thanks so much that was fast!

OK......