Answer:
m∠a + ∠120 = 180
m∠a = 60
m∠a + m∠b + m∠60 = 180
m∠b = 60
Explanation:
Part a
Since the measurements of a straight line is 180 degrees. Therefore m∠a and m∠120 should be added together to get a straight line which is 180 degrees
Part B
Since the sum of m∠a and ∠120 = 180 then arranging the equation we get
m∠a + ∠120 = 180
m∠a = 180 - 120
m∠a = 60
Part C
We know that the sum of all the interior angles of a triangle is always equal to 180 therefore ∠a, ∠b and ∠60 should be added because they are the interior angles
Part D
If the sum of all the interior angles of a triangle is always equal to 180 then arranging the equation
∠a + ∠b + ∠60 = 180
We already know ∠a so put the values
∠60 + ∠b + ∠60 = 180
∠b = 180 - 60 -60
∠b = 60