John wants to make 15 L of a 71% alcohol
solution by mixing together a 80% alcohol
solution and a 65% alcohol solution. How
much of each solution must he use?

80 percent alcohol mrans that in one liter we have 0.8 l of alcohol and 0.2 liter of water for example
65 percent ⇒0.65 liter of alcohol and 0.35 liter of water

For 71 percent alcohol we have the quantity wich is 15 liter

so :

15 liter⇒ 100 percent

x( the unkhown quantity)⇒ 71 percent

x = (15*71)/100 )= 10.65 liter of alcohol

so we want 10.65 liter of alcohol

here is a way :

lat's take 10 L of 80 percent alcohol and 4liters of the other one

10*0.8+4*0.65 = 10.6

we just need 0.05 liter of alcohol

add 0.0625 L of the 80 percent liter alcohol to get 10.65

John wants to make 15 L of a 71% alcoholsolution by mixing together a 80% alcoholsolution and a 65% alcohol solution. Howmuch of each solution must he use?​