14 days ago, Zoe had a total of 150 pink and silver cards. 40% of her cards were silver cards. Today, her grandmother gave her some more cards. As a result, her pink cards increased by 30%. Now, 50% of her cards are silver cards. How many silver cards did her grandmother give her?
| |
Silver cards |
Pink cards |
Total
cards |
| Before |
2 u |
3 u |
150 |
| Change |
+ 1.9 u |
+ 0.9 u |
|
| After |
3.9 u |
3.9 u |
|
Comparing the
pink cards and
silver cards in the end |
1 |
1 |
|
40% =
40100 =
25 Silver cards : Pink cards = 2 : 3
Increase in the number of pink cards
= 30% x 3 u
=
30100 x 3 u
= 0.9 u
50% =
50100 =
12 In the end
Silver cards : Pink cards = 1 : 1
Number of cards at first
= 3 u + 2 u
= 5 u
5 u = 150
1 u = 150 ÷ 5 = 30
Number of silver cards that Zoe received from her grandmother
= 3.9 u - 2 u
= 1.9 u
= 1.9 x 30
= 57
Answer(s): 57
