Warren has 90% as many pens as Seth. If Warren gives away 25% of the pens and Seth gives away 50% of his pens, they will have 423 pens altogether. How many pens do the two of them have?
| |
Warren |
Seth |
Total |
Comparing Warren
and Seth at first |
9x4 =
36 u |
10x4 =
40 u |
|
| Before |
4x9 =
36 u |
2x20 =
40 u |
|
| Change |
- 1x9 =
- 9 u |
- 1x20 =
- 20 u |
|
| After |
3x9 =
27 u |
1x20 =
20 u |
423 |
90% =
90100 =
910 25% =
25100 =
14 50% =
50100 =
12 The number of pens that Warren has at first is repeated. Make the number of pens that Warren has the same. LCM of 9 and 4 is 36 u.
The number of pens that Seth has at first is repeated. Make the number of pens that Seth has the same. LCM of 10 and 2 is 40 u.
Number of pens in the end
= 27 u + 20 u
= 47 u
47 u = 423
1 u = 423 ÷ 47 = 9
Total number of pens that the two of them have
= 36 u + 40 u
= 76 u
= 76 x 9
= 684
Answer(s): 684
