Mr. A divided our cake so I got 2/5th of it. If remaining cake was divided equally among 5 more friends so each got 150g, what was the weight of full cake?

3/5 of Cake = 5 x 150 g, Cake Weight = 5/3 x 750 g = 1250g

Important, it is not required to calculate the weight of cake given to you. The inverse of "remaining" fraction can directly give weight.

Important: Eye-catchers include "2/5" and "5 more friends". Do not be tempted by numbers that look relevant within question.