Answer:
The linear equation for the total combination age is

Explanation:
If Jane is X years old today. And her brother is 4 years older then her brothers age is,
X+4.
Jane's age after 7 years = X+7
Jane's Brothers age after 7 years = (X+4)+7
So after seven years their combined age will be 24, Lets write this in an equation form,

So the linear equation for the total combination age is,
