How do I do this problem

Question

For each problem familiarize yourself with the situation. Then translate to mathematical language. You need not actually solve the problem; just carry out the first two steps of the five step strategy. Complete some of the solution.

 

The sum of two numbers is 91. One of the numbers is 9 more than the other. What are the numbers?

 

 

Answer 1

The numbers are n and n + 9.

n + n + 9 = 91

Answer 2

You don't know what the two numbers are, so they are the unknowns you are trying to find.  Label one of the numbers as x, the other as y.  Now translate the words to math.  When you have two unknowns (x and y), you will need two equations to solve the problem.

 

The sum of the two number is 91:  x + y = 91

 

One of the numbers is 9 more than the other;  x = y + 9  (you could also do y = x + 9.  Either one will work)

 

You now have your two equations.