For this case we can propose an equation that will allow us to find the price of one of the books knowing the price of the other.
x: Let the variable that represents the price of the book with a green sticker
y: Let the variable that represents the price of the book with a yellow sticker
According to the statement we have:


Finally, we can substitute the price of one of the books and clear the value of the other as the case may be.
Answer:

You express the values in which the teacher or tutor or whatever assigned you.
Answer:
The steps 1-7 have been explained
Step-by-step explanation:
The steps are;
1) We will verify that the population standard deviations are known and that the population is normally distributed which means the sample size must be a minimum of 30.
2) We will state the null and alternative hypothesis
3) We will determine the critical values from the relevant tables
4) From the critical values gotten, we will determine it's corresponding region where it can be rejected.
5)We will calculate the value of the test statistic from the formula;
z = [(x1' - x2') - (μ1 - μ2)]/√[((σ1)²/n1) + ((σ2)²/n2)]
6) If the value of the test statistic gotten from step 5 above falls in the region of rejection noted in step 4,then we will reject the null hypothesis
7) After rejection of the null hypothesis, we will now give a decision/conclusion on the claim.
The answer that you’re looking for is B & D