Can someone me understand how to do this ?

16. you're planning to buy a boat, a motor, and some miscellaneous boating equipment. the boat costs $325, the motor costs $225, and the equipment costs $79. if you've saved $438 toward these purchases, how much more do you need to save? a. $181 b. $281 c. $291 d. $191

If f(x)=3x+1 and f^-1=x-1/3, then f^-1(7)=

Compare the cost of the bike trips from the two companies shown.for both the cost in a linear function of the number of days which statements is true