I think you did everything correctly.
I think the problem is that the problem is impossible.
Health experts agree that cholesterol intake should be limited to 300 mg or less each day. Three ounces of shrimp and 2 ounces of scallops contain 156 mg of cholesterol. Five ounces of shrimp and 3 ounces of scallops contain 45 mg of cholesterol less than the suggested maximum daily intake. Determine the cholesterol content in an ounce of each item.
the two equations i got were
3x+2y=156
5x+3y=45
so from there, i eliminated the x's out and i got my y as 645...is it me or is that a little much? so i plugged that back into the original equation and i got my x as -378.....weird again. i plugged the x and y back into the equation and ta-da! the both worked but they dont seem like reasonable answers...do they?