Math plz help plz plz

In the field of thermodynamics, rankine is the unit used to measure temperature. one can convert temperature from celsius into rankine using the formula c= r/1.8 - 273, what is the temperature in celcius corresponding to r degrees rankine.

43lbs of tomatos cost $387. how much would 41lbs cost

Which of the following is the best first step in solving the equation below? 4+2㏒³x=17