Hello, math34a!

This is a standard "mixture problem".I have two cans of paint.

Can A has 9 parts of blue paint to one part of yellow paint.

Can B is 20% blue and the rest is yellow.

How much paint should I use from each can to obtain

4 liters of paint which is half blue and half yellow.

Answers in liters.

Can A is 90% blue.

Can B is 20% blue.

. . We want 4 liters of mixture which contains 2 liters of blue.

Let = number of liters from can A.

. . It contains: . liters of blue.

Then = number of liters from can B.

. . It contains: . liters of blue.

Together, this mixture will contains 2 liters of blue.

Thereis our equation: .