How can a ratio be like a fraction? How can it be different from a fraction?

What are the constants in this expression? -10.6+9/10+2/5m-2.4n+3m

Trish receives $450 on the first of each month. josh receives $450 on the last day of each month. both trish and josh will receive payments for next four years. at a discount rate of 9.5 percent, what is the difference in the present value of these two sets of payments?

What is the rate of change of a line that passes through (2,-5) and (6,-2)?