Quote:
On Sunday, in Alexa’s stable, the ratio of the number of ponies to the number of horses was 4:5. On Monday, she bought 35 more ponies and horses, then the ratio of ponies to horses became 5:8. Assuming that no animal left the stable or died and stable had ponies and horses only, what is the least number of horses that were there in the stable on Sunday?
A. 35
B. 55
C. 60
D. 65
E. 70
Let me explain.
On Sunday, the ratio of p (the number of ponies) to h (the number of horses) was 4:5.
On Monday, Add 35 more ponies and horses. Then, the ratio of the number of ponies to the number of horses was 5:8.
So I test the choice
A: the number of horses on Sunday = 35
On Sunday, the ratio p to h = 28/35
On Monday, the ration p to h can be 30/48
Therefore, the additional p and h = 2+13 = 15 On Monday, the ration p to h can be 35/56
Therefore, the additional p and h = 7+21 = 28 On Monday, the ration p to h can be 40/64
Therefore, the additional p and h = 12+29 = 41Out.B: the number of horses on Sunday = 55
On Sunday, the ratio p to h = 44/55
On Monday, the ration p to h can be 45/72
Therefore, the additional p and h = 1+17 = 18On Monday, the ration p to h can be 50/80
Therefore, the additional p and h = 6+25 = 31On Monday, the ration p to h can be 55/88
Therefore, the additional p and h = 11+33 = 44OutC: the number of horses on Sunday = 60
On Sunday, the ratio p to h = 48/60
On Monday, the ration p to h can be 55/88
Therefore, the additional p and h = 7+28 = 35So I choose C.
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