Write a shell script to scan two variables and to display their sum, mul, div, sub and modulo division as per the user choice

read a;
read b;
echo Enter 1 for addition, 2 for subtraction, 3 for multiplication, 4 for division, 5 for modulo ;
read c;
if [ $c = 1 ]
then
echo ` expr $a + $b `;
elif [ $c = 2 ]
then
echo ` expr $a - $b `;
elif [ $c = 3 ]
then
echo ` expr $a \*  $b `;
elif [ $c = 4 ]
then
echo ` expr $a / $b `;
elif [ $c = 5 ]
then
echo ` expr $a % $b `;
else
echo Enter number from 1-5 ;
fi