Question 911999
x second number
1st +  2nd + 3rd  = 40
(x+5) + x + (x+5)/2 = 40
2(x+5) + 2x + (x+5) = 80
2x+10 + 2x + x + 5 = 80
5x = 65
x = 13, second number.  First 18{{{13+5}}}, third 9{{{18/2}}}
And...checking
sum = 40