Please I kinda know the answers but it’s just that I have to simply some and I don’t know how... can someone please give me the answers

Write a function that matches the description. a cosine function has a maximum of 5 and a minimum value of -5. f (r) =

Ricardo ran the 400 meter race 3 times his fastest time was 54.3 seconds his slowest time was 56.1 seconds if his average time was 55.0 seconds what was his time for the third race

Mat bought a phone for $100. he has to pay $30 per mouth. if he has paid $640 in total, how many mouth has he had the phone?