You can put this solution on YOUR website! Let x, x+1 & x+2 be the 3 numbers.
x(x+1)=(x+2)^2-19
x^2+x=x^2+4x+4-19
x-4x=4-19
-3x=-15
x=-15/-3
x=5 ans. for the smallest number.
5+1=6 ans. for the next number
5+2=7 ans. for the third number.
Proof:
5*6=7^2-19
30=49-19
30=30