Calculus
posted by Mulan .
1)Suppose Q = x^3 y^2 . If [dQ/dt] = −1 and [dx/dt] = 2, find [dy/dt] when
x = 4 and y = 5 .
[dy/dt] =______
2)Let A be the area of a circle with radius r. If [ dr / dt ] = 2, find [ dA / dt ] when r = 3

I will do one, and be happy to check your thinking.
q=x^3 y^2
dq/dt= 2x^2 y dy/dt+ 3y^2x^2 dx/dt
put in dq/dt, dx/dt, and find dy/dt .. 
i don't get it..
dq/dt isnt it 3x^2y
and i don't get the part where you put 3y^2x^2 how many exponents are there