Answer:
Area of trapeze= (B+b):2×h
Therefore : (7+10):2×4=34
Good luck!
When you see a "%" you need to ask " a percent of what"?
Here, it's a percent of the original prize, so the discount is 20% of the original prize, that is 20% of 35.
20% is also 20/100 or 1/5, so we can calculate this like this:

so the discount is 7 dollars.
X-4/2 = 10
x+-2=10
x-2=10
x-2+2=10+2
x=12
Notice the picture below
x = 1 and y = -1
now... recall your SOH CAH TOA

now.. what's the value for "r" or the radius? well, using the pythagorean theorem