At the bird park were some adults.
12 of the number of tourists was equal to 2 times the number of locals. When another 23 locals entered and 77 tourists left, the ratio of the number of tourists to the number of locals become 7 : 5. Find the number of locals at the bird park at first.
| |
Make p the same
(1)x5 = (3) |
Tourists
(1) |
Locals
(2) |
Make p the same
(2)x7 = (4) |
| Before |
20 u |
4 u |
1 u |
7 u |
| Change |
- 385 |
- 77 |
+ 23 |
+ 161 |
| After |
35 p |
7 p |
5 p |
35 p |
12 of the tourists = 2 times of the locals
1x22x2 of the tourists =
2x11x1 of the locals
Make the numerators the same. LCM of 1 and 2 is 2.
24 of the tourists =
21 of the locals
Tourists : Locals = 4 : 1
Make p the same.
(3) = (4)
20 u - 385 = 7 u + 161
20 u - 7 u = 161 + 385
13 u = 546
1 u = 546 ÷ 13 = 42
Number of locals at the bird park at first
= 1 u
= 42
Answer(s): 42
