Eight gallons of a salt solution consists of 25% salt. It is the result of mixing a 60% solution with a 20% solution. How many gallons of each of the solutions was used? Let x= the number of gallons of the 60% solution and y= the number of gallons of the 20% solution. The corresponding modeling system is {x+y=80.6x+0.2y=0.25(8) . Solve the system by using the method of substitution.