Answer:
a = 18
b = 56
Explanation:
Since we know that the sum of angles of a triangle is 180 degrees,
To find a, we look at the triangle at the left,
It must satisfy,
a + 63 + 99 = 180
a = 180 - 63 - 99
a = 18
For b,
we note that the angle supplementary to 99 is, (since adding them both gives a straight line i.e. adding them must equal 180),
i.e., lets call the angle x,
then,
99 + x = 180
x = 180 -99
x = 81
then for the triangle on the right, we have,
b + 43 + 81 = 180
b = 180 - 43 - 81
b = 56
We could have also found b by considering the entire (big) triangle that is cut into two,
in this case,
63 + b + (a + 43) = 180
63 + b + (18 + 43) = 180
b = 180 - 63 - 18 - 43
b = 56
Hence we get the same answer