Answer: Eric earned $7
Step-by-step explanation:
Let's define:
R = money that Robert earned.
E = Money that Eric earned.
Now we want to find how much money did Eric earn.
We know that:
R = $10 = 2*E - $4
Whit this equation, we can find the value of E. So we must isolate the variable E in one side of the equation:
2*E = $10 + $4 = $14
E = $14/2 = $7
Eric earned $7
