Find Pairs of Numbers that Fit a Simple Equation

In this activity, we will look at equations with two unknowns.

 

a and b stand for two numbers, which could be different or the same.

 

Look at this equation.

a + b = 8

It tells you that a added to b is 8.

 

We are looking for any two numbers that add to 8 in order to satisfy (fit) the equation.

If a is 6, b will be 2.

If a = 2, b = 6

If a = 4½, b = 3½

 

 

Example

a - b = 7

Which of these solutions satisfy the equation?

a = 7, b = 0

a = 0, b = 7

a = 10, b = 3

a = 10¾, b = 3¾

 

Answer

Put the given pairs into the equation to see if a - b is 7 or not.

 

a = 7, b = 0	fits because 7 - 0 = 7
a = 0, b = 7	does not fit because 0 - 7 = -7 (not 7)
a = 10, b = 3	fits because 10 - 3 = 7
a = 10¾, b = 3¾	fits because 10¾ - 3¾ = 7