The ratio of pears to grapefruits is 2 : 7. If 30 grapefruits are added, the ratio of pears to grapefruits will be 1 : 5. How many pears are there?
| |
Pears |
Grapefruits |
| Before |
2x1 =
2 u |
7x1 =
7 u |
| Change |
|
+ 30 |
| After |
1x2 =
2 u |
5x2 =
10 u |
The number of pears at first and in the end remains unchanged. Make the number of pears at first and in the end the same. LCM of 2 and 1 is 2.
Number of grapefruits added
= 10 u - 7 u
= 3 u
3 u = 30
1 u = 30 ÷ 3 = 10
Number of pears
= 2 u
= 2 x 10
= 20
Answer(s): 20
