Please show me the steps to solve this:

KE = ½ (900kg)*(20m/s)^2

Huh? There's nothing to solve. Just evaluate the numbers...

½ (900kg)*(20m/s)^2
= ½(900)(20)^2(kg)(m/s)^2
= (450*400) kg-m^2/s^2
= 180000 N-m
= 180KJ