A box contained black and yellow coins. There were 60% more black coins than yellow coins. When 65 more coins were poured into the box, the amount of black coins increased by 25% and the amount of yellow coins increased 90%. How many coins were in the box at first?
| |
Black coins |
Yellow coins |
Total coins |
| Before |
8 u |
5 u |
13 u |
| Change |
+ 2 u |
+ 4.5 u |
+ 6.5 u |
| After |
10 u |
9.5 u |
19.5 u |
100% + 60% = 160%
160% =
160100 =
85Number of more black coins that were poured into the box
= 25% x 8 u
=
25100 x 8 u
= 2 u
Number of more yellow coins that were poured into the box
= 90% x 5 u
=
90100 x 5 u
= 4.5 u
Total number of more coins that were poured into the box
= 2 u + 4.5 u
= 6.5 u
6.5 u = 65
1 u = 65 ÷ 6.5 = 10
Number of coins in the box at first
= 8 u + 5 u
= 13 u
= 13 x 10
= 130
Answer(s): 130
