Question

Renting a bicycle at a local Bike shop costs $30 for the first day and $10 for each additional day.

Answer 1

1.
a. If you rent the bike just one day you don't have an additional cost.
The equation looks like this:

c=30+(d-1)*10

b. c = 30+(5-1)*10 = 30+40=70

2. 
2x+3y+2(x-y)-3x=
2x+3y+2x-2y-3x=
x+y