Answer:
To rent a jet ski you need to pay $50 and to rent a kayak you need to pay $20
Step-by-step explanation:
Since both shops charge the same amount for each kind of vehicle, we will assign variables to the their cost. The cost of a jet ski will be "x" and the cost of the kayak will be "y". Therefore we can create a system of equations as shown below:
Will's shop:
12*x + 9*y = 780
Fun Rentals:
7*x + 11*y = 570

We can isolate "x" on the second equation, we have:

Applying this value on the first equation:
![12[\frac{570 - 11y}{7}] + 9y = 780\\\frac{6840 - 132y}{7} + 9y = 780\\\frac{6840 - 132y + 63y}{7} = 780\\ 6840 - 132y + 63y = 5460\\6840 - 69y = 5460\\69y = 1380\\y = 20](https://tex.z-dn.net/?f=12%5B%5Cfrac%7B570%20-%2011y%7D%7B7%7D%5D%20%2B%209y%20%3D%20780%5C%5C%5Cfrac%7B6840%20-%20132y%7D%7B7%7D%20%2B%209y%20%3D%20780%5C%5C%5Cfrac%7B6840%20-%20132y%20%2B%2063y%7D%7B7%7D%20%3D%20780%5C%5C%206840%20-%20132y%20%2B%2063y%20%3D%205460%5C%5C6840%20-%2069y%20%3D%205460%5C%5C69y%20%3D%201380%5C%5Cy%20%3D%2020)
Applying the value of "y" we found on the "x" equation above, we have:
Therefore to rent a jet ski you need to pay $50 and to rent a kayak you need to pay $20