Question

Susan's present age is x years . what will be her age 7 years from now ?​

Answer 1

Answer:

We are working with two people (Susan and her brother) and

two periods of time: (now and 3 years in the future)

Choose a variable and then write an expression for each person's age for each period of time. Remember, in 3 years time, they will both be 3 years older, so add on 3

Table form works well for this.

Susan's brother is younger, so let his age be x years,

××××Present age×××in 3 years

Brother: ×××x×××.×x(x+3)

Susan: ××x(x+10)×××x(x+10+3)=(x+13)

In 3 years time, she will be twice as old as her brother. so write an equation to show this:

2(x+3)=x+13 ← solve for x

2x+6=x+13

2x−x=13−6

x=7

The brother is 7 years old and Susan is 17

Check: In 3 years time:

Brother will be 7+3=10 and Susan will be 17+3=20

2×10=20