Which statement is true ? Also to what does the middle lines mean

Olga bought a new skirt that cost $20. sales tax is 5%. how much did olga pay, including sales tax? 7.

Adan has decided to purchase an $9000 car. he plans on putting 20% down toward the purchase and financing the rest at 7.9% interest rate for 3 years. find his monthly payment a) $225.29 b) $298.81 c) $204.78 d) $236.89

The function representing david's miles per month if f(m)= 115m + 5. what does the 115 represent