Hi try this code in bash,

read M
read R
read T
A=`expr $M + $R + $T`
B=2000
if [ "$A" -gt "$B" ]; then
echo "A is greater than 2000"
elif [ "$A -lt "$B ];
echo "A is less than 2000"
elif [ "$A" = "$B" ]; then
eho "A is equal to 2000"
fi