Question

if distance =3t-6t² find distance in 5 second

Answer 1

its easy.
given,t=5 seconds.
put the value of t in the given eqn.
distance=3(5)-6(5*5)
=15-150=-135.answer.

Answer 2

Substitute t=5  Then you get the answer. For your betterment, i gave only hint. Try it.