Answer:
x = 50
Explanation:
add all terms and set sum equal to 360
the 'hint' of (n-2)180 determines how many degrees there are inside the polygon; if 'n' equals the number of sides and the polygon has 4 sides then sum of interior angles is (4-2)180 or 2x180 which is 360
x + 10 + 3x + x + 2x = 360
combine like terms to get: 7x + 10 = 360
7x = 350
x = 50