If you download Photomath and scan your question it will give u the answer;)
Answer:
x=11
Step-by-step explanation:
Since the lines in the middle are parallel, we know that both sides are proportional to each other.
6:48 can be simplified to 1:8
Since we know the left side ratio is 1:8, we need to match the right side with the same ratio
We can multiply the ratio by 5 to match 5:3x+7
5:40
5:3x+7
Now we can set up the equation: 40=3x+7
Subtract 7 from both sides
3x=33
x=11
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 
T= sqrt(5/wc)
remove ( )
T= 5sqrt/wc
multiply by wc
Twc=5sqrt
divide by Tc
W= 5sqrt/cT
hope this helps