Answer:
3) 146 degrees
4) 471 degrees
5) x = 100 and 3x = 300
Step-by-step explanation:
all three are polygons whose sum of all interior angles can be found by using the formula (n - 2)*180 where 'n' refers to the number of sides
In #3 and 5 there are 5 sides, so (5 - 2)*180 = 3(180) giving a total of 540 degrees. Add all known angles and deduct from 540.
#4 has 7 sides, so (7 - 2)*180 = 1260 degrees. Add all known angles and deduct sum from 1260.
#5 Add all integers plus 'x' + '2x' to get 240 + 3x = 540
