The sum of Sharon's and John's ages is 70. Sharon is 4 times as old as John.

If you let $\displaystyle{s}=\usepackage{cmbright}\Huge\$ Sharon's age and $\displaystyle{j}=\usepackage{cmbright}\Huge\$ John's age, then the problem can be represented by a system of equations. Which of the following shows a graph of this system and the solution to this problem?