In a school, the ratio of adults to the number of children is 7 : 5.
The ratio of the number of boys to the number of girls is 5 : 3.
There are 70 more boys than girls.
How many people are there in the school?
| Adults |
Children |
| 7 x 8 |
5 x 8 |
| |
Boys |
Girls |
| |
5 x 5 |
3 x 5 |
| 56 u |
25 u |
15 u |
The number of children is the combined repeated identity.
Make the number of children the same using the LCM of 5 and 8.
LCM of 5 and 8 = 40
Number of more boys than girls
= 25 u - 15 u
= 10 u
10 u = 70
1 u = 70 ÷ 10 = 7
Number of people
= 56 u + 25 u + 15 u
= 96 u
= 96 x 7
= 672
Answer(s): 672
