Fred has 70% as many pens as Will. If Fred gives away 25% of the pens and Will gives away 50% of his pens, they will have 410 pens altogether. How many pens do the two of them have?
| |
Fred |
Will |
Total |
Comparing Fred
and Will at first |
7x4 =
28 u |
10x4 =
40 u |
|
| Before |
4x7 =
28 u |
2x20 =
40 u |
|
| Change |
- 1x7 =
- 7 u |
- 1x20 =
- 20 u |
|
| After |
3x7 =
21 u |
1x20 =
20 u |
410 |
70% =
70100 =
710 25% =
25100 =
14 50% =
50100 =
12 The number of pens that Fred has at first is repeated. Make the number of pens that Fred has the same. LCM of 7 and 4 is 28 u.
The number of pens that Will has at first is repeated. Make the number of pens that Will has the same. LCM of 10 and 2 is 40 u.
Number of pens in the end
= 21 u + 20 u
= 41 u
41 u = 410
1 u = 410 ÷ 41 = 10
Total number of pens that the two of them have
= 28 u + 40 u
= 68 u
= 68 x 10
= 680
Answer(s): 680
