The y-intercept of the line whose equation is 3x + 2y = 7

You'll have to get this equation back to the y=mx+b form to find your y intercept. Start by getting y alone.

3x + 2y = 7
-3x        -3x
2y = -3x + 7

Since why has a 2 in front of it, you now need to divide the entire equation by 2 to get y completely alone.

2y = -3x +7
/2
y= -3/2x + 7/2

Normally, you'd want to simplify the fractions but that is the smallest you can get it to be. Your y intercept is 7/2.