L: 1750, M:1750-480=1270 Lisa gave some stamps to Mark so Lisa now has 1750-x and Mark has 1270+x. Mark also has 3 times as many as Lisa now: (1750-x)*3=1270+x 5250-3*x=1270+x 4*x=3980, x=3980/4, x=995 So Lisa gave 995 stamps to Mark. At first Mark had 1270 stamps. Lisa now has 1750-995=755 stamps.
First, let's figure out what amount of stamps Mark originally had.
1750 - 480 = 1270
Mark originally had 1270 stamps.
Now, we have to figure out how many stamps Lisa has.
s = stamps
1270 + s = (1750 - s)3 1270 + s = 5250 - 3s Add 3s to both sides. 1270 + 4s = 5250 Subtract 1270 from both sides. 4s = 3980 Divide both sides by 4. s = 995
