Riordan had 150 more cards than Michael. Riordan gave 20% of his cards to Michael. Michael in return gave 50% of his cards to Riordan. In the end, Michael had 372 less cards than Riordan. How many cards did Riordan have at first?
| |
Riordan |
Michael |
Comparing Riordan
and Peter at first |
150 more |
|
| Before |
5 u + 150 |
5 u |
| Change 1 |
- 1 u - 30 |
+ 1 u + 30 |
| After 1 |
4 u + 120 |
6 u + 30 |
| Change 2 |
+ 3 u + 15 |
- 3 u - 15 |
| After 2 |
7 u + 135 |
3 u + 15 |
20% =
20100 =
1520% x 150
=
20100 x 150
= 30
50% x 30
=
50100 x 30
= 15
50% x 6 u
=
50100 x 6 u
= 3 u
Michael had 372 less cards than Riordan in the end. If another 372 cards are given to Michael, both will have the same number of cards.
7 u + 135 = 3 u + 15 + 372
7 u - 3 u = 15 + 372 - 135
4 u = 252
1 u = 252 ÷ 4 = 21
Number of Michael's cards at first
= 5 u
= 5 x 21
= 105
Answer: 105
