My cousin needs with his homework,and i have no clue what he learned,can you ?

Well for all of them, you divide the perimeter by number of sides. ♡

For each problem, you take the perimeter and divided it by the number of sides the shape has.

Example: (number 4) the shape has 5 sides and a perimeter of 50 in. so you divide the two numbers to get the length of each side which is 10 in. 

You know that you add $3 for every video. You start off with one video for $8. Then you add 3 every time. So for every video you add $3. So 2 videos would be $11. 6 videos would be $23. 7 would be $26. 8 would be $29. 9 would be $32. 10 would be $33. 11 would be $36. 12 would be $39. 13 would be $42. 14 would be $45. Then fifteen would be $48. The equation would be 48 = 3x + 8. This is because you start off with 8 dollars for one video and add 3 for each. Then end product would be $48 after 15 videos.