Answer:
C. 20
Step-by-step explanation:
45 + 5x + 35 = 180
5x + 80 = 180
subtract 80 from both sides
5x = 100
divide by 5
x = 20
Answer: 13 1/3
Step 1: Find the LCD
Step 2: Add the fractions
Step 3: Simplify
If the geometric series has first term
and common ratio
, then its
-th partial sum is

Multiply both sides by
, then subtract
from
to eliminate all the middle terms and solve for
:



The
-th partial sum for the series of reciprocal terms (denoted by
) can be computed similarly:




We're given that
, and the sum of the first
terms of the series is

and the sum of their reciprocals is

By substitution,

Manipulating the
equation gives

so that substituting again yields

and it follows that

its is the same as multiplying normally .
For example 1-2-3-4-5-6-7-8- 2 times 2
you just take the starting number (2) and times it by the other number (2) and youll get 4