\(If $a\equiv 16\pmod{37}$ and $b\equiv 21\pmod{37}$, then for what integer $n$ in the set $\{0,1,2,\ldots,35,36\}$ is it true that$$a-b\equiv n\pmod{37}~?$$ \)
a mod 37 = 16 b mod 37 = 21 (a - b) mod 37 = n, solve for n
a = 16 and b = 21 (a - b) mod 37 = n
(16 - 21) mod 37 = - 5
n =37 + (-5) = 32
+223 
