Answer:
∠ EBF = 98°
Step-by-step explanation:
(3x - 15) and (2x + 10) are vertically opposite angles and are congruent, then
3x - 15 = 2x + 10 ( subtract 2x from both sides )
x - 15 = 10 ( add 15 to both sides )
x = 25
3x - 15 = 3(25) - 15 = 75 - 15 = 60°
The exterior angle of a triangle is equal to the sum of the 2 opposite interior angles.
∠ EBF is an exterior angle of the triangle , then
∠ EBF = 60° + 38° = 98°
Solution :
Let A = Economics, B = Mathematics
n(A) = 311, n(B) = 243, 
a). So, 
= 311 + 243 - 135
= 419
b). n(A only) = 311 - 135
= 176
n(B only) = 243 - 135
= 108
Exactly one of these two courses
= 0.568
c). Neither economics nor mathematics
= 0.162
