Opal and Gabby have some notebooks in the ratio 5 : 13. Opal has 80 less notebooks than Gabby. How many notebooks must Gabby give to Opal so that they will have the same number of notebooks?
| |
Opal |
Gabby |
Total |
| Before |
5 u |
13 u |
18 u |
| Change |
+ 4 u |
- 4 u |
|
After |
1x9 =
9 u |
1x9 =
9 u |
2x9 =
18 u |
The total number of notebooks remains unchanged. Make the total number of notebooks at first and in the end the same. LCM of 2 and 18 is 18.
Difference in the number of notebooks at first
= 13 u - 5 u
= 8 u
8 u = 80
1 u = 80 ÷ 8 = 10
Number of notebooks that each of them had in the end
= 18 u ÷ 2
= 9 u
Number of notebooks that Gabby must give to Opal
= 9 u - 5 u
= 4 u
= 4 x 10
= 40
Answer(s): 40
