Question

The value of a car is inversely proportional to its age. if a car is worth ​$49004900 when it is 55 years​ old, how old will it be when it is worth ​$35003500​?

Answer 1

Multiply them together to get a constant.
Then divide the constant  by the new value and it will give you the new age.
You can just use substitution to find any variable.

constant = age * value
value = constant / age
age = constant / value