Question

what is the value of c?
40°
3c
5c - 21°
write your answer as an integer or as a decimal rounded to the nearest tenth.
c =
submit

Explanation:

Step1: Use exterior angle theorem

The exterior angle of a triangle equals the sum of the two non-adjacent interior angles. So:
$$5c - 21 = 40 + 3c$$

Step2: Isolate variable terms

Subtract $3c$ from both sides:
$$5c - 3c - 21 = 40$$
$$2c - 21 = 40$$

Step3: Isolate constant terms

Add 21 to both sides:
$$2c = 40 + 21$$
$$2c = 61$$

Step4: Solve for c

Divide both sides by 2:
$$c = \frac{61}{2}$$

Answer:

$30.5$