Suppose 4x^2 +16y^2 =100, where x and y are functions of t. \text { (a) If } \frac{d y}{d t}=\frac{1}{4}, \text { find } \frac{d x}{d t} \text { when

} x=3 \text { and } y=2 \text { . } \text { (b) If } \frac{d x}{d t}=4, \text { find } \frac{d y}{d t} \text { when } x=-3 \text { and } y=2 \text { . }