The angles of a pentagon are x^\circ, 2x^\circ, (x + 60)^\circ, (x + 10)^\circ, (x -10)^\circ. Find the value of x.
A
40
B
60
C
75
D
80
E
90
Verified Correct Answer: D.
Step-by-Step Mathematical Solution
Sum of ∠s in a pentagon = (n - 2)180 = 540^\circ
x^\circ + 2x^\circ + x^\circ + 60^\circ + x^\circ + 10^\circ + x^\circ - 10^\circ = 540^\circ
6x^\circ + 60^\circ = 540^\circ; x = 80^\circ
Source: Myschool Past Questions Archive (Record #23109)