For a parallel line the slope of the lines/equations will be the same but for perpendicular line the slope will be the negative reciprocal
-(1/4)*x+b
b=2-(-1/4)*8
1/4, 2/5, 0.5, 0.75
1/4 is 0.25
2/5 is 0.40
Then order from least to greatest.
a. Notice that
1/(1*2) = 1/2 = 1 - 1/2
1/(2*3) = 1/6 = 1/2 - 1/3
1/(3*4) = 1/12 = 1/3 - 1/4
and so on, which suggests the n-th term of the sum can be written as

Then the sum itself is telescoping:



b. The proof is trivial:

so the formula found in (a) is correct.