Question

Lisa had 1750 stamps. Mark had 480 fewer stamps than Lisa. Lisa gave some stamps to Mark. Now Mark has three times as many stamps as Lisa. How many stamps did Mark have at first? How many stamps does Lisa have now?

Answer 1

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

Now, subtract 995 from 1750.

1750 - 995 = 755

Lisa now has 755 stamps.

Answer 2

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.