Operations Management help needed. please check your work, provide explanation if possible. if it's right I'll give you a like.

The final assembly line for a small scale auto manufacturer is where the tires are mounted. The shop first removes a protection bumper that has guarded the wheel assemble which it can do at a rate of 10 different cars per hour. It can then put on new tires at a rate of 12 cars in an hour. To get the tires in proper condition, the shop inflates the tires with air (or nitrogen if required), which it can do at a rate of 9 cars per hour. Lastly, the shop ensures it did good work by testing the car. The shop is able to test 7 cars each hour. What is the activity time for the bottleneck in minutes? (Round you answer to one decimal place.)