Shopping cart work Part C $|$ Problem

A shopper pushes a grocery cart $20\mathrm{.}0$ m at constant speed over a level floor, against a $35\mathrm{.}0$ N frictional force. His pushing force is directed at an angle of $25$ degrees below the horizontal.

What is the work done on the cart by the normal force from the ground?

$01$

$5001$

$-500.$

$634.$J

$-634!$

$7001$

$-7001$