(ax + b)/c ≤ b
ax+b ≤ cb
ax ≤ cb - b
x ≤ (cb-b)/a
total income= 2R-C-2P
R= omoun tof rent paid by each tenant = $700
C= cable bill = $100
P = Phone bill = $50
Replace the values:
Total income = 2(700)-100-2(50)
total income= 1,400-100-100 = 1,400-200= $1,200
Total income =$1,200
Answer should be 1.85 x 10^18
Order of the people does not affect the total number of ways. Thus, we use combinations.
Total combinations: 20C5 = 15,504 ways.