JS_점수 평균 내기

const aClass = [10, 20, 30, 40, 50];
const bClass = [10, 20, 80, 40, 90];

function grade(gNum) {
let total = 0;

for (let i = 0; i < aClass.length; i++) {
total += aClass[i];
}
const avr = Math.floor(total / aClass.length);
console.log("평균:" + avr);

if (gNum > avr) {
up = gNum - avr;
console.log(평균보다${up}점 높네ㅋㅋ);
} else if (gNum < avr) {
down = avr - gNum;
console.log(평균보다${down}점 낮네ㅜㅜ);
}
return;
}
grade(10);