Sixteen gallons of a salt solution consists of 40% salt. It is the result of mixing a 55% solution with a 25% solution. How many gallons of each of the solutions was used? Let x= the number of gallons of the 55% solution and y= the number of gallons of the 25% solution. The corresponding modeling system is {x+y=160.55x+0.25y=0.4(16) . Solve the system by using the method of substitution.