If a plane can travel 500 miles per hour with the wind and 400 miles per hour against the wind, find the speed of the wind and the speed of the plane in still air . what is the speed of the wind? pleas helpp asap

Suppose that a households monthly water bill (in dollars) is a linear function of the amount of water the household uses (in hundreds of cubic feet, hcf). when graphed, the function gives a line with slope of 1.65. if the monthly cost for 13 hcf is $46.10 what is the monthly cost for 19 hcf?