var arr = []
for (var i = 1; i <= 30; i++) {
arr.push(2 * i)
}
console.log(arr)
var newArr = []
var add = 0
for (var j = 0; j < arr.length; j++) {
add += arr[j];
if ((j + 1) % 5 === 0) {
newArr.push(add / 5)
add = 0
}
}
console.log(newArr)