How do you do it.. i don't understand this

First calculate x.
since its an isosceles triangle, and the 2 isosceles sides r same so the base angles are the same
therefore 7x + 5 = 9x - 13
5 + 13 = 9x - 7x
2x = 18
x = 9
so when we have x = 9, just use the angle sum of triangle to calculate y.
4y + 7x9 + 5 + 9x9 -13 = 180
4y + 136 = 180
y= 11
so there u have it, x is 9 ans y is 11

The first one, i believe, would be correct. all the others have one thing in common, and that's that they have repeating numbers. in the second one, x and y have repeating 6's and 3's, and in the third, x and y have repeating 6's as well. in the last one, there are repeating 3's. the first one has no repeating numbers.