Ifound a place that will give me a 20% discount if i spend over $50 my bill is 75%.how much money will i save?

Anyone know these questions? i need ,.

X-10/4 when x = –18 a 7 b –2 c –7 d 2

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 .