5 days ago, Abi had a total of 120 gold and silver erasers. 25% of her erasers were silver erasers. Today, her mother gave her some more erasers. As a result, her gold erasers increased by 20%. Now, 50% of her erasers are silver erasers. How many silver erasers did her mother give her?
| |
Silver erasers |
Gold erasers |
Total
erasers |
| Before |
1 u |
3 u |
120 |
| Change |
+ 2.6 u |
+ 0.6 u |
|
| After |
3.6 u |
3.6 u |
|
Comparing the
gold erasers and
silver erasers in the end |
1 |
1 |
|
25% =
25100 =
14 Silver erasers : Gold erasers = 1 : 3
Increase in the number of gold erasers
= 20% x 3 u
=
20100 x 3 u
= 0.6 u
50% =
50100 =
12 In the end
Silver erasers : Gold erasers = 1 : 1
Number of erasers at first
= 3 u + 1 u
= 4 u
4 u = 120
1 u = 120 ÷ 4 = 30
Number of silver erasers that Abi received from her mother
= 3.6 u - 1 u
= 2.6 u
= 2.6 x 30
= 78
Answer(s): 78
