math
posted by Michelle .
Hi,
I have a math problem that I can't understand how to write the equation for. The question says: a ball is thrown upwards from an initial height of 20 meters at an initial velocity of 10 meters per second. Write an equation for the height (h) of the ball at time (t). My teacher gave us this equation, y= gt + vo t (for time) +ho. That doesn't make sense with the problem. I'm not suer what format I would put the equation in. Can someone please help me solve this?

ho=20m
vo=10m/s
g=9.8m/s^2
Use the equation. 
Thank you.