How to compare floats and ints

if ((weight >=240 ) && (weight<=265))
{
  val = 172;
  bolt = "AG-4.500" ;
}

else
{
 val = 186;
  bolt = "Uknown";
}

The else there is only associated with the last if. The last if is false so the else executes and makes val= 186 and bolt = "AG-4.500".

To fix it make every if statement after the first one else if.

if ((weight >= 30) && (weight<=35))
{
  val = 0;
  bolt = "AL-0.500" ;
}

else if ((weight >= 39) && (weight<=45))
{
  val = 14;
  bolt = "AL-0.750" ;
}
else if ((weight >= 46) && (weight<=52))
{
  val = 28;
  bolt = "AL-1.000" ;
}

Ans so on. You should end up with one if, several else if and one else.