Suppose Joe earned three times as much as Marty during the summer. Together they earned $210. How much did each earn? (write a system of equations)

Let’s say Joe earned = x, and Marty earned y

Together they earned $210
So, x + y = $210

If Joe earned 3 times as much as Marty then:
x = 3y

Thus we can substitute and say,
3y + y = 210
4y = 210
y = 52.5

x = 3y = 3(52.5)
x = 157.5

Joe earned $157.5 and Marty earned $52.5