What number is the same as 7 tens and 20 ones

You are on a cycling trip around europe with friends. you check the weather forecast for the first week. these are the temperatures for the week. sun mon tues wed thurs fri sat 16°c 20°c 24°c 28°c 28°c 23°c 15°c what is the mean temperature forecast for the week?

Which one is the correct answer, and why?

Me i'm timed right now! a. (0,-5)b. (0,-3)c. (0,3) d. (0,5)