Question 986856
An object is propelled vertically upward with an initial velocity of 20 meters per second. The distance s (in meters) of object from ground after t seconds is s=-4.9t( squared) +20t. When will object be 15 meters above ground? 

Is this set up like 15=-4.9tsquared+20t??
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Yes, exactly like that.
Solve for t.
There might be 2 values for t, 1 going up, another descending.