2x+42=4x
42=2x
21=x
Answer: x=21
If the diameter is -3 to 3 then the diameter is 6 so the radius is 3. the equation would be x^2 + y^2 = 9. fyi i found this somewhere else online. i do this a completely different way and am not sure if this is correct.
He earned $15.20. Just multiply the 2.00x4 and the 2.40x3