There are 25% more red cards than grey cards in a bag. After Rael removed 40% of the red cards and increased the number of grey cards by 20%, there are now 180 fewer red cards than grey cards. Find the number of grey cards at first.
|
Red |
Grey |
Before |
5 u |
4 u |
Change |
- 2 u |
+ 0.8 u |
After |
3 u |
4.8 u |
Number of red cards in percentage
= 100% + 25%
= 125%
125% =
125100 =
54Number of red cards that Rael removed
= 40% x 5 u
=
40100 x 5 u
= 2 u
Number of grey cards that Rael increased
= 20% x 4 u
=
20100 x 4 u
= 0.8 u
Number of red cards in the end
= 5 u - 2 u
= 3 u
Number of grey cards in the end
= 4 u + 0.8 u
= 4.8 u
Number of fewer red cards than grey cards in the end
= 4.8 u - 3 u
= 1.8 u
1.8 u = 180
1 u = 180 ÷ 1.8 = 100
Number of grey cards at first
= 4 u
= 4 x 100
= 400
Answer(s): 400