you cannot get that answer.... when you divide. Put the number into a fraction first so, it makes it easier to see what you are doing. So,

.Now simplify the cross off the zero from the top and the bottom to get

. So,

will give you 0.83333333333...3.
2x - 6 = 20
2x = 20 + 6
2x = 26
x = 26/2
x = 13 <==
For this we almost have the following equation:

We must match the equation to zero:

From here, we clear the value of t.
We have then:

We discard the negative root because we are looking for time:
Answer:
it will take him to reach the ground about:

seconds