Question 1067261
THE FIFTH-GRADER REASONING (mental math):
If 20 salads cost as much as 15 sandwiches,
1/5 of that money would be the cost of
4 salads or 3 sandwiches.
If you could have bought 15 sandwiches,
but only need 12, which is 3 less sandwiches,
you could use the money that would pay for those 3 sandwiches
to buy 4 salads.