I suppose you mean

Differentiate one term at a time.
Rewrite the first term as

Then the product rule says

Then with the power and chain rules,

Simplify this a bit by factoring out
:

For the second term, recall that

Then by the chain rule,

So we have

and we can simplify this by factoring out
to end up with

An hour and 15 minutes i believe. not 100% though
$50000 + (9%x(10000x$20)=
$50000 + (9%x$200000)=
$50000 + $18000=
$68000
(1/3)2= 2/3 cups butter
(1/3)24= 8 oz marshmallows
(1/3)14= 4 2/3 cups rice crispy