Achemistry student needs to make 60 liters of a 30% alcohol solution. he has a 20% alcohol solution and a 40% alcohol solution in the lab. how many liters of each strength does he need to mix together
*the system of equations i did was: a+b=60 & .2a+.4b=18. i may be wrong but i seriously need

When y’all answer can y’all explain too !

What is the the greatest common factor ?

Exclude leap years from the following calculations. (a) compute the probability that a randomly selected person does not have a birthday on october 4. (type an integer or a decimal rounded to three decimal places as needed.) (b) compute the probability that a randomly selected person does not have a birthday on the 1st day of a month. (type an integer or a decimal rounded to three decimal places as needed.) (c) compute the probability that a randomly selected person does not have a birthday on the 30th day of a month. (type an integer or a decimal rounded to three decimal places as needed.) (d) compute the probability that a randomly selected person was not born in january. (type an integer or a decimal rounded to three decimal places as needed.)