A local hamburger shop sold a combined total of 518 hamburgers and cheeseburgers on Monday. There were 68 more cheeseburgers sold than hamurgers. How many hamburgers were sold on Monday

We know there are 68 more cheeseburgers sold than hamburgers. Therefore:
Let x = hamburger
x + 68 = cheeseburger
x + x + 68 = 518
2x + 68 = 518
2x = 450, x = 225 hamburgers

No, to decide whether two triangles are similar it is not enough to know that two pairs of corresponding angle measures in the triangle are equal.

That is because two triangles are similar if the only difference is size.

So, when you know that two corresponding angles are equal, the third angle is also (necessarily) equal. This is, the all three angles are equal and it could be the case that also the three corresponding side lengths are equal, which means that the triangles are not similar but congruent.