One number is five less than another. The sum of the two numbers is 45. Find the two numbers and solve an algebraic equation

Question

I know the answer is 25 and 20 i just need to know how to write this as an algebraic equation. 

Answer 1

Let x and y be the two unknown numbers.

• One number is five less than another:  x = y - 5
• The sum of the two numbers is 45:  x + y = 45

 

x + y = 45

 

Substitute y-5 in place of x:

 

y - 5 + y = 45

2y - 5 = 45

2y = 50

y = 25

 

Find x:

x = y-25

x = 25 - 5

x = 20

Answer 2

n and n-5 are the numbers

n+(n-5)=45

solve for n, or...

n and n+5 are the numbers

n+(n+5)=45

solve for the numbers

either way gives you the answers