You have to use implicit derivative
dy / dx = y'
xy^3+y=3x
y^3 + 3xy^2 y' + y' = 3
[3xy^2 + 1) y'= 3 - y^3
3 - y^3
y' = ----------------- <-----------answer
3xy^2 + 1
The correct place for it in the .04
200,000,000+40,000,000+9,000,000+100,000+4,000+300+30
hope I helped :)