Computation Race 3

Let's have a race between brains and calculators. If you are using a calculator, you must find answers to all the problems with a calculator. If you're using your brain, you are welcome to use paper.

1.
75
–50
 2.
5
x2
 3.
5
x3
4.
5
x4
 5.
5
x5
 6.
25
x2
7.
25
x3
 8.
25
x4
 9.
150
–25
10.
10
+10
+10
+10
 11.
4
x10
 12.
$.25
+$.50
13.
$.25
+$.75
 14.
$1.50
–$.25
 15.
$2.00
–$.75