At an amusement park a person spends $30 on admission and food and then goes on r number of rides that cost $2 each

The question is find the equation, in the function and standard notations, that represent the amount spent in the range of 0 to 5 rides.

Constant cost: $30
Independent variable, number of rides: r
Variable cost: $2r

Total spend, s(r): 30 + 2r

Function: s(r) = 30 + 2r, for 0 ≤r ≤ 5  this is the function notation

Standard form: s(r) is the dependent variable = s

s = 30 + 2r => s - 2r = 30 =>

s + (-2)r = 30, for 0 ≤ r ≤ 5 this is the standard form