What does the "y" mean in a slope intercept form equation (y=mx+b)?

Find the value of x. give reasons to justify your solutions! h ∈ ig

Maria solved an equation as shown below. what is the solution to maria’s equation?

The height above the ground (in feet) of a ball dropped from the top of a 30-foot-tall building after t seconds is given by the polynomial: ? 16t^2+30 what is the height of the ball after 1/2 second?