Thank you!!But may i know the formula for time?

there isnt a formula for time technically. what you have are three equations (v=u+at, s=ut+(at^2)÷2 and v^2=u^2+2as), of which you see what the question gives you such that they can fit into which formula to get the answer (ie, you have the values needed for v=u+at but not s=ut+(at^2)÷2 so you cannot use the second equation to find t, and v^2=u^2+2as is irrelevant to finding t)

Ok tysm!!