## What Is x and y?

Hello, Everyone! How  R U?

I want to give U a math problem, high school algebra or college freshman algera level.

Let x and y be two unknown variables.

Question : If

x+y=7

x-y=3,

then,

what is x and y?

Solution:

x=___

y=___

Hint: solve it as system of linear equations.

If  U have forgotten about this level of math, please think about the question by guess: how many ways to have two numbers sum as 7, then find the pair of numbers with difference as 3.

for example,  7=7+0=6+1=5+2=4+3=3+4=2+5=1+6=0+7, I have told you 8 ways of sum to 7.

Solutions: x=5, y=2.

check:

5+2=7,

5-2=3. Thus solution is correct.

There are many ways of doing it, Doraz commented exactly how to solve it graphically, mathematically, or using methods of substitutions, cancellations. We can also solve it using graphing Ti-83 calculator…Any way. I give this question which is mediate hard, thus I prefer not to make it too abstract to majority readers. Let me know if you have questions!

Outstanding job, everyone who joined the fun! 15 of U did wonderfully in math computation on this one.