Can someone plz me solve this simultaneous equations

The cash price of a television is $580.the hire-purchase price of the television is $865.the hire-purchase price is an initial deposit of n% of the cash price and 6 equal monthly payments of $120.find the value of n.

The average daily maximum temperature for laura’s hometown can be modeled by the function f(x)=4.5sin(πx/6)+11.8 , where f(x) is the temperature in °c and x is the month. x = 0 corresponds to january. what is the average daily maximum temperature in may? round to the nearest tenth of a degree if needed. use 3.14 for π .

Find the value of x to the nearest tenth.