Two sinusoidal waves on a string are defined by the wave

TII functions

$y_1=2\mathrm{.}00sin(20\mathrm{.}0x-32\mathrm{.}0t),y_2=2\mathrm{.}00sin(25\mathrm{.}0x-40\mathrm{.}0t)$

where $x,y_1,$ and $y_2$ are in centimeters and $t$ is in seconds.

$($a$)$ What is the phase difference between these two waves at the point $x=5\mathrm{.}00cm$ at $t=2\mathrm{.}00s?($b$)$ What is the positive $x$ value closest to the origin for which the two phases differ by $+-$ at $t=2\mathrm{.}00s?($At that location, the two waves add to zero.$)$