Hello from MrBillDoesMath!
Answer:
a) See Discussion below
b) Don't know what "m" refers to
Discussion:
Part a)
A triangle contains 180 degrees.
A + B + C = 180 (*)
where A is the angle inside the triangle.
From the diagram
B +C = 62 + 78 = 140
Substituting this in (*) gives
A + (140) = 180 => subtract 140 from both sides
A = 180 - 140 = 40
Now a line has 180 degrees so x + A = 180. But A = 40 (shown above) so x+ 40 = 180, or x = 140. That is, x = 140 - the sum of the measures of the two nonadjacent interior angles
Part b)
I can't answer this part is it is unclear what "m" refers to. Sorry.
Thank you,
MrB