What is the missing variable x^2+3x+c=7/4+c

If 30 lb of rice and 30 lb of potatoes cost ? $27.60? , and 20 lb of rice and 12 lb of potatoes cost ? $15.04? , how much will 10 lb of rice and 50 lb of potatoes? cost?

Jayne is studying urban planning and finds that her town is decreasing in population by 3% each year. the population of her town is changing by a constant rate.true or false?

Awindow washer cleans 42 windows in 2 hours. at this rate, how many windows did he clean in 180 minutes.