Question

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

Explanation:

Step1: Sum angles to 180°

$$3a + (8a - 6^\circ) + (a + 18^\circ) = 180^\circ$$

Step2: Combine like terms

$$3a + 8a + a - 6^\circ + 18^\circ = 180^\circ$$
$$12a + 12^\circ = 180^\circ$$

Step3: Isolate the variable term

$$12a = 180^\circ - 12^\circ$$
$$12a = 168^\circ$$

Step4: Solve for a

$$a = \frac{168^\circ}{12}$$

Answer:

$14^\circ$