consecutive numbers are 1 apart
they are
n,n+1,n+2
so the diffference of 4 times (n+2) and twice (n) is 5 times (n+1)
4(n+2)-2n=5(n+1)
expand/distribute
4n+8-2n=5n+5
2n+8=5n+5
minus 2n both sides
8=3n+5
minus 5 both sides
3=3n
divide by 3
1=n
n+1=2
n+2=3
the numbers are 1,2,3