the sum of two numbers is 21 and their difference is 5. What are the two numbers?

Question

Larger number 1st

 

smaller number 2nd

Answer 1

X+Y = 21 ---> Y = 21-x

 

X-y = 5

 

x - (21-x) = 5

 

2x - 21 = 5

2x = 26

x = 13

 

13 and 8

Answer 2

Hello, Joleigh,

 

Steps to setting up this word problem:  

Let x= one number and y= the other number

 

1.  Underline or highlight key words and numbers.

 

          x+y                        = 21                 x-y            =5

The sum of two numbers is 21 and their difference is 5.            Q:  What are the two numbers?

 

2.  Set up a system of equations:      x+y=21

                                                      x-y  =5            You want to eliminate one of the variables (x or y).

 

 

3.  Just add the two equations together.    x+y=21

                                                             x-y=  5 

                                                            2x   = 26        Solve for "x" by dividing both sides of the equation

 

by the number next to "x."   (2/2)x=26/2      x=13     (larger number)     

 

4.  You can find the smaller number by substituting x=13 into one of the original equations (x+y=22 or x-y=5) to solve for "y."   I will let you finish your problem.  Susan C.