Question 1202547: Horses sold for $400 each and ponies for only $100. Weir spent $4500 and bought 5 more horses than ponies. How many horses did she buy? Found 3 solutions by josgarithmetic, ikleyn, greenestamps:Answer by josgarithmetic(39630) (Show Source):
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Horses sold for $400 each and ponies for only $100.
Weir spent $4500 and bought 5 more horses than ponies. How many horses did she buy?
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Let x be the number of the horses.
Then the number of the ponies is (x-5).
Write the total money equation
400*x + 100*(x-5) = 4500 dollars.
Simplify and solve
400x + 100x - 500 = 4500
500x = 4500 + 500
500x = 5000
x = 5000/500 = 10.
ANSWER. 10 horses and 10-5 = 5 ponies.
CHECK. Check the total cost 10*400 + 5*100 = 4500 dollars. ! Precisely correct !
While a formal algebraic solution was probably wanted, note that you can get good mental exercise, and good problem-solving practice, by solving the problem informally using logical reasoning and simple mental arithmetic.
In this problem, she bought 5 more horses than ponies. Those 5 "extra" horses cost 5($400) = $2000.
Beyond that, there were equal numbers of horses and ponies with a total cost of $4500-$2000 = $2500.
The cost of one horse and one pony is $400+$100 = $500; to make the additional $2500 cost, the remaining number of horses and ponies must have been $2500/$500 = 5.
So the number of ponies she bought was 5, and the number of horses she bought was 5+5 = 10.