> How many stamps did Mark have at first?
We know that Lisa has 1750 stamps and Mark has 480 fewer than this, therefore subtract 480 from 1750 to get the number of stamps that Mark had at first:
1750 – 480 = 1270 stamps
> How many stamps does Lisa have now?
Let us say that x = the number of stamps that Lisa gave to Mark, therefore we can create the equation:
Mark = 3 * Lisa
480 + x = 3 (1750 – x)
480 + x = 5250 – 3x
4x = 4770
x = 1,192.50 stamps
So Lisa has now left with:
1750 – 1192.50 = 557.5 stamps ~ 557 stamps or 558