Brad average typing rate in words per minute is 21
1260 divided by 60 = 21
(In case you meant 30 minutes)
1260 divided by 30 = 42
17=5k-2
add 2 to both sides
19=5k
divide both sides by 5
19/5=k
19/5=3 and 4/5
we are given

Firstly, we will find all possible factors of 144

we can also write as

now, we can put exponent to over entire term

now, we can replace 144

now, sqrt will get cancelled with square
and we get

now, we can simplify it

.............Answer
If it's a negative exponent for example -6 the answer would be 1/x^-6. So if x is 10. Then 10^-6 is equal to 1/10^6 (One over ten to the power of 6 or One divided by 10 to the power six)