Hello. I don't understand the topic of discounts and markups. Could someone please help me understand how to solve math problems in this topic step by step? Asap?

1. there are 25 students who started computer programming in elementary school and 25 students who started computer programming in middle school. the first group had a mean final project grade of 95% and the second group had a mean final project grade of 92%. the line plot shows the differences after 10 rerandomizations. determine whether the difference in the means of the two groups is significant based on the line plot. explain your answer.

Atorch and a battery cost 2.50 altogether. the torch costs 1.50 more than the battery. what fraction of the total price is the torch? give your answer in its simplest form.

Amir wants to proportionally increase the size of a photo to create a poster for his room. the size of the original photo is shown. complete the statement and then answer the question to represent ways that amir can increase the size of his photo.