Question

f = ____
57°
51°
f°

Explanation:

Step1: Recall angle - sum property of a triangle

The sum of the interior angles of a triangle is 180°. So, we have the equation $f + 57+51=180$.

Step2: Solve for $f$

$f=180-(57 + 51)$. First, calculate $57+51 = 108$. Then, $f=180 - 108$.
$f = 72$.

Answer:

$72$