The correct answer of 16/38 simplified is 8/19
Answer:
There is a 99.99998% probability that at least one valve opens.
Step-by-step explanation:
For each valve there are only two possible outcomes. Either it opens on demand, or it does not. This means that we use the binomial probability distribution to solve this problem.
Binomial probability distribution
The binomial probability is the probability of exactly x successes on n repeated trials, and X can only have two outcomes.

In which
is the number of different combinatios of x objects from a set of n elements, given by the following formula.

And p is the probability of X happening.
In this problem we have that:

Calculate P(at least one valve opens).
This is 
Either no valves open, or at least one does. The sum of the probabilities of these events is decimal 1. So:


So


Finally

There is a 99.99998% probability that at least one valve opens.
1) given
2) definition of linear pair
3) definition of linear pair and supplementary
4) definition of supplementary supplementary angles add to 180
5) the measure of angle one plus the measure of angle 2 plus the measure of angle 3 equals 180
6) substitution in lines 4 and 5
7) the measure of angle one plus the measure of angle 2 equals measure of angle 4 by algebra and simplification
Answer: 731 days
Since 2018 is 2 years away from 2020, that is 730. Add 1 day, that is 731 days.
A mixed number is a number that has a whole number, and a fraction, so the mixed number that is equal to 7.6 is 7 6/10, simplified it would be 7 3/5