Answer:
The answer should be 1500g I think.
Answer: D
Step-by-step explanation:

First calculate after tax tire price
$390.60 / 4 = $97.65 after tax price per tire
take the $97.65 divided by 90
97.65 / 90 = 1.085
1.085 is the rate of tax he paid per tire
Couldn't it be 54, 53 52, or 51
Use elimination
-x - y = -9
x - y = 3
Add both equations
-2y = -6, y = 3
-x -(3) = -9
-x = -6, x = 6
Final answer: x = 6, y = 3