How do I do this trigonometry problem? or where do I even start.

In the sixth grade 13 out of 20 students have a dog if there are 152 sixth grade students how many of them have a dog

What would be the reasons for lines 3 and 4? a. addition property; subtraction property b. addition property; solve c. substitution property; subtraction property d. substitution property; prove

Determine the required value of the missing probability to make the distribution a discrete probability distribution. x p(x) 3 0.23 4 ? 5 0.51 6 0.08 p(4) = nothing  (type an integer or a decimal.)