Question posted by Gazelle from Singapore:

Paul and May shared $264 equally. After Paul spent 4 times as much money as May, May had 3 times as much money left as Paul. How much money had Paul left?

Answer:

Step 1: Draw 2 equal boxes.

Step 2: Mark out the part spent by May.

Step 3: Mark out the parts spent by Paul.

Step 4: Mark out the part Paul had left as 1 part versus the 3 parts May had left.

(Take note that 1 shaded part is not the same size as 1 unshaded part.)

Step 5: From the model, we see that 3 shaded parts is equal to 2 unshaded parts. We then convert all parts (both shaded and unshaded) into identical units by sub-dividing the parts (with dotted lines).

Step 6:From the model, we found that

22 units ------------> $264

1 unit ------------> $264 / 22 = $12

3 units ------------> 3 X $12 = $36

Thus, Paul had $36 left.