Kleiza's Problem Solving

I am learning to draw a picture to help me solve a problem.

The problem that I had to solve was:

Larenzo has 3 times as many marbles than Janet does. Janet has 7 marbles. How many marbles does Larenzo have?

Miss Hughes came into our class to do problem solving. I drew three boxes with seven marbles in each box. I got the answer it was 21. It was really easy to do this problem