shell parsing is useful only for integer division:
var1=8
var2=4
echo $((var1 / var2))
output:
2
instead your example:
var1=3
var2=4
echo $((var1 / var2))
ouput:
0
it’s better to use bc:
echo "scale=2 ; $var1 / $var2" | bc
output:
.75
scale is the precision required