Michigan Algebra I Sept. 2012

If one apple plus one banana costs$1.25 and one apple plus two bananas costs$2.00, how much does it cost for one banana? How much does it cost for one apple?

Step 1. Use a and b as the cost for apples and bananas, write two equations.

a + b = 1.25

a + 2b = 2.00

Step 2. Pretend the two equations create columns to add down and see if either variable will cancel.

Since neither variable will cancel automatically, move on to the next step.

Step 3. Determine which variable will cancel, then multiply one equation so that the variable will cancel.

In this equation the two "a" variables have the same coefficient and would cancel with opposite signs. Therefore, multiply one equation by -1.

a + b = 1.25

-1(a + b = 1.25)

-a - b = -1.25