You need 455 ml of a 75% alcohol solution. on hand, you have a 25% alcohol mixture. you also have a 90% alcohol mixture. how much of each mixture will you need to add to obtain the desired solution?
x ml - 25% alcohol mixture y ml - 90% alcohol mixture
x+y = 455
0.25x ml alcohol in x ml of 25% alcohol mixture 0.9y ml alcohol in y ml of 90% alcohol mixture 0.75*455= 341.25 ml alcohol in 455 ml of 75% alcohol mixture
0.25x+0.9y=341.25
System of equations: x+y = 455 /*(-0.25) ------> -0.25x-0.25y = -0.25*455 0.25x+0.9y=341.25 -0.25x-0.25y=-113.75 0.25x+0.9y=341.25 Add both equations 0.25x+0.9y-0.25x-0.25y=341.25-113.75 0.65y =227.5 y=227.5/0.65 = 350 ml of 90% alcohol mixture
