Richard saltwood’s car averages 620 miles on its 20-gallon tank of gas. if richard runs out of gas and a mechanic comes to his rescue with 2 1/4 gallons of gas, determine how far his car can go

Well first you have to divide 620/20 which is 31. So his car goes 31 miles per gallon so you have 2 gallons and .25 of a gallon. So first off 2*31=62 miles then the 1/4 or .25. Multiply the 31 by .25 which is 7.75 now add 62 and 7.75 and you get how far his car can go. 

62+7.75=69.75 miles

X must be greater than 0 and y must be less than 0.
I hope this helped.