Question

x=7/2a 9/4b-16,sendo a=2 e b=4

Answer 1

$a=2~e~b=4\\\\\\x= \frac{7}{2}a + \frac{9}{4}b -16\to \\\\ x= \frac{7}{2}.2 + \frac{9}{4}.4 -16\to \\\\ x= \frac{14}{2} + \frac{36}{4} -16\to \\\\ x=7+9-16\to\\\\ x=16-16\to \\\\ \boxed{x=0}$