Sarah has $70 to rent a bike in the city. It costs $12 per hour to rent a bike. There is an additional fee for a helmet of $4 for the entire ride.

this is the formula: v = the value of investment at the end of the time period

p = the principal amount (the initial amount invested)

r = the annual interest rate

n = the annual frequency of compounding (how many times a year interest is added)

t = the number of years the money is invested

^ means raise to the power of

cross multiplying, we get :

⇒ (3) × (5) = (9) × (x)

⇒ 15 = 9x