Your answer is

because the numbers raised to negative powers must be flipped over the divisor to become positive. Then, when multiplying 2 and z, you add their exponents.
19 8/10 and if its simplified, 19 4/5
The answer is 48.66, as the hundreth place is the 5, but you must round it up to a 6 since the 7 is larger than 5
Area is Base times Height.
the height is 5, and the base is 7 so our equation is
5×7
the answer is 35