What is Sydney's age?

Question

Devaughn is
7
years older than Sydney. The sum of their ages is
47
. What is Sydney's age?

Answer 1

Let x = Sydney's age

Let x + 7 - Devaughn's age

 

x + x + 7 = 47

2x + 7 = 47

2x = 40

x = 20 years

x + 7 = 27 years

Answer 2

First, write your system of equations based on what is given:

 

D=S+7

D+S=47

 

Next, substitute equation 1 into equation 2:

 

S+7+S=47

2S=40

S=20

Sydney is 20.