Exercise 19 Page 354

Let's call the first number a and the second number b. The phrase the sum of two numbers is 22 can be written algebraically by equating 22 with the sum of a and b. a+ b=22 The second phrase, their difference is 12, can be written algebraically by equating 12 with the difference a- b. a- b=12 Combining these equations, we get a system of equations. a+ b=22 & (I) a- b=12 & (II) Since b and - b have opposite coefficients, we will solve this system using elimination by addition.

Now that we have found the value of a, we can substitute it into Equation (I) to solve for b.

We have found that the numbers are 5 and 17.