Answer:
∠A = 48
∠B = 58
∠BCA = 74
Step-by-step explanation:
m∠BCD is an exterior angle of a triangle while m∠A and m∠B are opposite interior angles of m∠BCD
Exterior angles of a triangle are equal to the sum of the opposite interior angles, hence m∠BCD = m∠A + m∠B
Knowing this we can create an equation to solve for y
∠BCA = 106° , ∠B = 3y + 22 and ∠A = 4y
If m∠BCD = m∠A + m∠B then 106 = 3y + 22 + 4y
106 = 3y + 22 + 4y we now solve for y
combine like terms ( 3y + 4y = 7y )
106 = 7y + 22
subtract 22 from both sides
84 = 7y
divide both sides by 7
12 = y
Now we can find the measures of ∠A and ∠B by plugging in the value of y into their expressions
∠A = 4y
y = 12
∠A = 4(12) = 48°
∠B = 3y + 22
y = 12
∠B = 3(12) + 22
3 * 12 = 36
∠B = 36 + 22 = 58°
Finally we want to find the measure of ∠BCA
∠BCA and ∠BCD are supplementary angles
Supplementary angles add up to 180°
Hence ∠BCA + ∠BCD = 180
∠BCD = 106°
∠BCA + 106 = 180
subtract 106 from both sides
∠BCA = 74°°
