The problem
Answer provided by our tutors
Every letter typed into the solver is treated as an algebraic variable (it is also noteworthy to point out that variables are case-sensitive, hence 'C' and 'c' would be treated as different variables). From what I see in your inquiry the following equation needs to be solved for 'r': S=C+rC
...so enter the equation in directly, click on the 'Solve' button and choose 'r' to solve for:
