media.js

const [_,__,...args] = process.argv

const isEven = (_, i) => (i % 2 === 0)
const isOdd = (_, i) => (i % 2 !== 0)

const parsedArgs = args.map(arg => parseInt(arg))

const scores = parsedArgs.filter(isEven)
const weights = parsedArgs.filter(isOdd)

const getScore = (n, p) => n * p
const getScoresSum = (s, w) => 
  s.reduce(( acc, score, index) => 
    acc + getScore(score, w[index])
  ,0)

const getWeightSum = (weights) => 
  weights.reduce((acc, weight) => 
    acc + weight
  , 0)

const getMedia = (s, w) => getScoresSum(s, w) / getWeightSum(w)

console.log(getMedia(scores, weights))