How to find two consecutive numbers whose squares differ by 15?

Let x is the first no. then the other no. will obviously be (x+1)

according to question,
(x+1)²- x²= 15
x² +2x+1 - x² = 15 ( using (a+b)²= a²+ b² + 2ab )
2x + 1 = 15
2x = 14
x = 7

hence numbers are x = 7 and x +1 = 7+1 = 8
also 8²-7² = 64-49 = 15

hence the numbers are 7 and 8

hope it helped