Please help! i will give brainliest or whatever if you help :)

Can someone check if i did this right since i really want to make sure it’s correct. if you do you so much

Express the following as a function of a single angle. cos(60) cos(-20) - sin(60) sin(-20)

It is saturday morning and jeremy has discovered he has a leak coming from the water heater in his attic. since plumbers charge extra to come out on the weekends, jeremy is planning to use buckets to catch the dripping water. he places a bucket under the drip and steps outside to walk the dog. in half an hour the bucket is 1/5 of the way full. what is the rate at which the water is leaking per hour?