Irene R. answered 01/10/20
BS in Mechanical Engineering and Certified math teacher for 13 years
Let's let c represent the NUMBER of cats at the shelter on Thursday and d represent the NUMBER of dogs. Since there are a total of 37 animals , we can write:
c + d = 37
Then since it costs $2.50 a day for each cat and $7.50 per day for each dog, we can represent the total money spent by:
2.50c + 7.50d = $182.50
To solve these two equations with two unknowns, use substitution.
From the first equation we can write that c = 37 - d
Substitute this expression for c into the second equation:
2.50c + 7.50d = 182.50
2.50 (37 - d ) + 7.50d = 182.50
Solve for d using inverses operations, combining like terms, and the distributive property :
92.50 - 2.50d + 7.50d = 182.50
92.50 + 5d = 182.50
92.50 + 5d - 92.50 = 182.50 - 92.50
5d = 90
5d / 5 = 90 / 5
d = 18 dogs
Then for the number of cats: c + d =37
c + 18 = 37
c = 19 cats