Answer:
x = 79
y = 12
Step-by-step explanation:
x + y = 91
x - y = 67
=> x = (91 + 67) : 2 = 79
=> y = (91 - 67) : 2 = 12
P/s: I don't know how to explain what I just did actually, since we learn how to solve this kind of problem in primary at my place already so it's like a blurry memory about how I learn it. If the math problem is to find 2 numbers, knowing their sum and the difference already, this is how to solve it:
=> Larger number: (Sum + difference) : 2
=> Smaller number: (Sum - difference) : 2
If you can memorize it, good for you! If not then it's alright, this is just a nice tips from me to you. You'll have more advantages in solving these kind of math problem if you can memorized these 2 formulas.
