Question

Two numbers have the sum of 1212 and the difference of 518. What are the two numbers?

Answer 1

The answers are 347 and 865. To solve this problem you set up two equations,
x+y=1212 and x-y=518. You then get the second x by itself by adding y to both sides. You then have x+y=1212 and x=y+518. After this you substitute the x into the first equation and have y+518+y=1212. Then simplify to 2y=694 and y=347
Now that y=347 you put it in the original equation. Solve and get that x=865

Answer 2

694
you just subtract 1212 by 518
694+518=1212