That would be c 4x^3-x^2+3x+13
A subtraction problem can be turned in to an addition problem because of negative numbers. Take 5-2=3 for example. If you change 5-2 into an addition problem then you would but he addition sign and a negative sign on 2. This will then leave you with the problem looking like 5+ -2. If you add 5 and -2 you will still get three.
1.75 Grams is what I got. Every 1 Milligram = 0.001 Gram.
Hope it helps :)