I too get the same. What is the actual OA ?

a= (7,3) and b=(x,8) and distance ab=13

using distance formula, (x-7)^2 + (8-3)^2=13^2
Solving we get, x=19,-5 since x cannot be < 0 we can have it as 19.

- Deepak

Just use your knowledge of 5 12 13 right triangle to solve this. Whenever the hypotenuse of a right triangle is 13 its legs got to be 5 and 12. So draw the right triangle and figure out which is which. The problem gave 5 away because 8-3= 5 from the y axis. So the horizontal leg is 12. But if you start from 7, you count 12 and that puts you to 19. So the x coordinate is 19.

i got this question in princeton prep test and the OA is 12.