14 days ago, Ivory had a total of 175 blue and black cards. 20% of her cards were black cards. Today, her cousin gave her some more cards. As a result, her blue cards increased by 40%. Now, 50% of her cards are black cards. How many black cards did her cousin give her?
| |
Black cards |
Blue cards |
Total
cards |
| Before |
1 u |
4 u |
175 |
| Change |
+ 4.6 u |
+ 1.6 u |
|
| After |
5.6 u |
5.6 u |
|
Comparing the
blue cards and
black cards in the end |
1 |
1 |
|
20% =
20100 =
15 Black cards : Blue cards = 1 : 4
Increase in the number of blue cards
= 40% x 4 u
=
40100 x 4 u
= 1.6 u
50% =
50100 =
12 In the end
Black cards : Blue cards = 1 : 1
Number of cards at first
= 4 u + 1 u
= 5 u
5 u = 175
1 u = 175 ÷ 5 = 35
Number of black cards that Ivory received from her cousin
= 5.6 u - 1 u
= 4.6 u
= 4.6 x 35
= 161
Answer(s): 161
