Write a system of equation to model each situation

Question

Write a system of equation to model each situation.solve by any method.

 

one antifreeze solution is 20 alcohol. Another antifreeze solution is 12% alcohol. How many liters of each solution should be combined to make 15 L of antifreeze that is 18% alcohol.

Answer 1

x = liters at 20% alcohol

y = liters at 12% alcohol

 

(0.20)x + (0.12)y = (0.18)(15 L) = 2.7 L

x + y = 15 L

 

The system to solve is

 

0.20x + 0.12y = 2.7

x + y = 15

 

The solution is

 

x = 11.25 L at 20%

y = 3.75 L at 12%