Ruth buys 20 pencils for $20. some cost $4,some $0.25 and some $.50 each. at least one of each. How many of each price?

Answer 1

If there are x,y,z of each cost, we have

x+y+z = 20
4.00x + 0.25y + 0.50z = 20.00

Since we have only two equations, there are multiple solutions. Let's work with knowing x. Then we have

y = 14x-40
z = 60-15x

Since y and z must be positive, we need

x >= 3 and x < 4. So, x=3, and we have

3 at $4.00
2 at $0.25
15 at $0.50