Hey guys I need a little help with this problem.

A rocket is fired from the ground into the air. After 10 seconds, the rocket is 150 feet in the air. After 50 seconds, the rocket is back down to 90 feet, and after 112 seconds, 30 feet.

1. Write the equation in standard form. This one I put it into a matrix and got: y = .005x^2-1.813x+167.609

2. how many seconds will the rocket be back to the ground?

No idea how to solve this.