Please check the picture.
Answer: An inequality is a mathematical or arithmetic phrase that is not equal; this inequality prohibits the equal sign. Instead, inequalities are expressed with greater than (>), less than (<), equal to or greater than (≥) or equal to or less than (≤).
You need this key result: in any polygon, the sum of the interior angles is

where
is the number of sides of the polygon.
Your polygon has seven sides, and the measures of all angles are given. So, we can write

Again, we've simply written that the sum of all interior angles is the number of sides, minus two, times 180.
We can simplify both sides: we sum like terms on the left hand side, and we easily compute the right hand side:

and we can solve this equation for
by dividing both sides by 30:

Finally, the required angles is 
Answer:
160 is the answer because 8x20 is 160 also 20÷400 is 20 so that made pretty good sense