Question 387137
x = one number,
x = s + 5, and x = 2t.
Then x + s + t = 45.  By substitution, 
x + x - 5 +x/2 = 45;
2x + x/2 = 50;
5x/2 = 50;
5x = 100;
x = 20, one number,
s = x - 5 = 15, the second number, and 
t = x/2 = 10, the third number.