1. D
2. A
3. C
I'll answer the last two in a minute.
The top one. they can't be expressed in a fraction or decimal
A two-digit number is twice the sum of its digit. If the tens digit is 7 less than the unit digit, find the number.
Let x= the unit digit
Then y= the tens digit
<span>And 10y+x= the number
</span>x+y= the sum of the digits
<span>Now we are told that 10y+x=2(x+y) ------1st equation </span>
<span>We are also told that y=x-7 ----------- 2nd Equation </span>
<span>So our equations to solve are: </span>
(1) 10y+x=2(x+y)
<span>(2) y=x-7
</span>
Hope it helps
15. 75 s̶i̶n̶c̶e̶ 20.00 p̶o̶u̶n̶d̶s̶ - 4a̶n̶d̶ 25 p̶o̶u̶n̶d̶s̶ e̶q̶u̶a̶l̶ 15.75 p̶o̶u̶n̶d̶s̶
Answer:
0.006% probability that the final vote count is unanimous.
Step-by-step explanation:
For each person, there are only two possible outcomes. Either they vote yes, or they vote no. The probability of a person voting yes or no is independent of any other person. So we use the binomial probability distribution to solve this question.
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 combinations of x objects from a set of n elements, given by the following formula.

And p is the probability of X happening.
Random voting:
So 50% of voting yes, 50% no, so 
15 members:
This means that 
What is the probability that the final vote count is unanimous?
Either all vote no(P(X = 0)) or all vote yes(P(X = 15)). So

In which



So

0.006% probability that the final vote count is unanimous.