2 : If z=f(x, y), where f is differentiable, x=g(t), y=h(t), and g(6)g′(6)=7=−7h(6)h′(6)=5=−5fx(7,5) fy(7,5)=6=6 Find dz/dt when t=6.

Mabel paid $2.95 for a granola bar dimes and quarters. she used five few were quarters then dimes. how many dimes and quarters did she use to pay for the granola bar.