The sum of the interior angles of any polygon with n sides
is given by this formula:
THE SUM OF THE INTERIOR ANGLES = (n-1)×180°
A pentagon has 5 sides, so
1. substitute n=5 in that formula to
find the sum of the interior angles.
2. write the sum of all 5 interior angles, by putting
+ signs between each pair, like this:
40+117+83+(7x + 30)+8x
3. Write an equal sign after that and put what you got
in step 1 on the right side of the equal sign.
4. Solve the equation for x.
Edwin
