For every question can you please go step by step

1.If (x+y)^2=7x^3y^4, find dy/dx by implicit differentiation

2.Find the equation of the tangent line to3x^2+6xy-y^2=-9 at (0,3)

3.A company's sales volume y (in millions of dollars) is related to its advertising expenses x (in thousands of dollars) by 15y-20x+xy=0. Find the rate of change of the sales volume with respect to advertising expenseswhen its expenses is10,000. Interpret your answer.

Answers 1) (21X^2y^4-2x-2y)/(2x+2y-{28x^3y3})

2) y=3x+3

3) 12/25=0.48. There is an approximate increase in the sales volume of $480,000 when $11,000 is spent on advertising