Can someone tell me whats wrong here with this code?

function prefixedSum(prefix, …numbers){

let sum = 0;

for (let num of numbers){

sum += num;

}

return ‘${prefix}: ${sum}’;

}

undefined

prefixedSum('sum: ')

“${prefix}: ${sum}”

prefixedSum('Sum: ')

“${prefix}: ${sum}”

prefixedSum(‘Sum’, 1,2,3,4,5)

“${prefix}: ${sum}”

why am i not getting the result here?

Ps: I have a $sign before {prefix} and {sum}