Answer
Yolanda exerts a force of $766~N$ on the elevator floor.
Work Step by Step
Let $F_N$ be the normal force of the elevator pushing up on the person in the elevator. Let $M$ be the person's mass.
$\sum F = Ma$
$F_N-Mg = Ma$
$F_N = M~(g+a)$
$F_N = (64.2~kg)~(9.80~m/s^2 + 2.13~m/s^2)$
$F_N = 766~N$
The elevator floor pushes up on Yolanda with a force of $766~N$. By Newton's third law, Yolanda exerts a force of $766~N$ on the elevator floor.
