I need help with these equations!

Given the following sampling distribution of one mean with a sample size 49, from a normally distributed population, find the population standard deviation, o.79828588912497

Awasher and a dryer cost $701 combined. the washer costs $51 more than the dryer. what is the cost of the dryer?

Rose bought a new hat when she was on vacation. the following formula describes the percent sales tax rose paid b=t-c/c