Answer:
Let the amount she has on the fourth day be $x$. Then adding the money spent in 4 days, we get:
$
\begin{aligned}
71+62+59+x = 64\times 4 \\
192+x = 256 \\
x =64
\end{aligned}
$ So the greater amount of money she could spend on day 4 is $\$64$ .