A: When you multiply two numbers, their exponents add.
So,

Since 64^1/2 multiplied by itself is 64, then it is the square root of 64.
B: The area is irrational. 7 * √7 is irrational.
It is okay to take the inverse of both side given that you remember to exclude the value that make the denominator zero which is in this case r=-1
X = 80
y = 85
If you look at only the left triangle, you can see that x is part of one of the angles. The 3 interior angles of the triangle add up to 180 degrees, so subtracting the other two angles, you get x + 30 = 110, or x = 80.
The same method can be used for the other triangle to find y.