Lets call our integers:
x, x+1 and x+2
the product of the smaller two integers is 5 less than 5 times the largest integer: this means
x(x+1) +5= (x+2)5
taking things out of the brackets:
xx+x+5= 5x+10
putting everything on one side:
xx+x -5x +5-10= 0
calculating:
xx+-4x -5= 0
we can put it into brackets:
(x+1)(x-5)=0
So we have x=-1 (which can't be, it has to be positive)
or x=5, which is the answer!
