Could someone help me to understand this please? It would mean a lot

A: AD

B: 25x15=375

Step-by-step explanation:

A: AD is parallel because the lines are the same.

B: AB = 25mm

BC = 15mm

25x15 = 375mm

The image below is for reference to Question B.

, and

for

step-by-step explanation:

we can analyze the pattern at which the terms increase. let us denote , , , so that we can call

note the following:

the pattern: to get the next term value, we just add the next term number (e.g. 1st, 2nd, to the previous term value (term values are the given numbers in the question, 1, 3, 6, 10, 15,

from , to get to , we add

from , to get to , we add

etc.

we need to form a recursive formula, a formula that has the next term as a function of the previous term. so a possible recursive formula can be

, and for