Solution for https://www.learnshell.org/en/Shell_Functions

script.sh

#!/bin/bash
# enter your function code here
function ENGLISH_CALC {
  case $2 in
  	"plus") echo "$1 + $3 = $(($1 + $3))";;
    "minus") echo "$1 - $3 = $(($1 - $3))";;
    "times") echo "$1 * $3 = $(($1 * $3))";;
  esac
}

# testing code
ENGLISH_CALC 3 plus 5
ENGLISH_CALC 5 minus 1
ENGLISH_CALC 4 times 6