Cassandra measured her height as 63 inches. That is 6 inches less than 3 times her younger brother's height. How tall is her younger brother? Write an equation in the form px + q = r to represent this problem.
a) 3h - 6 = 63
b) 3h + 6 = 63
c) 3h = 63 + 6
d) 3h = 63 - 6