A rock is thrown upward at a speed of 10 metres per second. The height of the rock above the ground is given by the formula h=10t-2.0t². Where h is the height in metres above the ground and t is the time in seconds. Then what is height after 5 second?

If this took place on earth, I have no clue where you got this equation from, should have been

h =10t - 4.9t^2 , unless somebody changed the laws of gravity.

but,...

when t=5
h =10(5) - .2(25) = .....