Question

the diagram shows a triangle.
what is the value of c?
c = \square^\circ

Explanation:

Step1: Sum angles to 180°

$57 + (2c-10) + (c-11) = 180$

Step2: Simplify left side

$57 -10 -11 + 2c + c = 180$
$36 + 3c = 180$

Step3: Isolate 3c term

$3c = 180 - 36$
$3c = 144$

Step4: Solve for c

$c = \frac{144}{3}$

Answer:

$c = 48^\circ$