Unix if- else grade calculator [duplicate]

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I am working on my unix homework and I get an error if I enter a grade higher then 59.

Enter a numeric grade number when prompted "Please enter your grade " and receive the message "You got a(n) ", where grade is the letter grade you earned.

#!/bin/bash

echo "Enter your grade"

read grade

echo "Grade: " $grade

if [ $grade -le 59 ]

then

echo "You got an F"

elif [ $grade -ge 60 ]&&[$grade -le 69]

then

echo “You got a D”

elif [ $grade -ge 70 ]&&[$grade -le 79]

then

echo “You got a C”

elif [ $grade -ge 80 ]&&[$grade -le 89]

then

echo “You got a B”

elif [ $grade -ge 90 ]&&[$grade -le 100]

then

echo “You got an A”

else

echo"enter correct value"

fi