Javascript adding multiple arrays in a loop

I am trying to add multiple arrays in javascript. Here are my arrays I have made, and are working.

function getAmountSpent(){

    var amountSpent = ((Math.random() * 500) + 1);
    return amountSpent.toFixed(2)
}

function getGift(){
    var gift = ((Math.random()* 50) + 1);
    return gift.toFixed(2)
}

var names = ["Jeremy","Arun","Alisa","Rohan","Dana"];


var spent = [];
for (let i = 0; i < 5; i++) {
spent.push(getAmountSpent());
}

var gifts = [];
for (let i = 0; i<5; i++) {
gifts.push(getGift());
}

What I need help with is adding these arrays in a new function. I have began writing the code, and I am not sure what is wrong.

var totals =[];
for (let i=0; i<5; i++) {
totals.push(getSumTotals())
}

function getSumTotals(a){
    totals= spent+(spent * gifts);
    return totals.toFixed(2)


}

From what you can see, I am trying to add up the totals much like this:

totals[0] = spent[0] + (spent[0] * gifts[0]);
totals[1] = spent[1] + (spent[1] * gifts[1]);
totals[2] = spent[2] + (spent[2] * gifts[2]);
totals[3] = spent[3] + (spent[3] * gifts[3]);
totals[4] = spent[4] + (spent[4] * gifts[4]);

if it helps, the professor added guided instructions for function getSumTotals(a) stating:

  This function will return the sum of the elements in array a.
  You will be passing the array that holds your totals to
  the parameter a. Be sure to treat the values in a as numbers.

I am not sure if this helps but here is the output to my document. Current Total should equal (spent) + (spent * gifts). For instance, for Jeremy in this example, current total should equal: $36.55 + ($36.55*0.0626) = $38.83. Since there are many variables involved, I am not 100% sure what I should write for function getSumTotals(a)

The parameter "a" is a placeholder because I am not sure how many parameter values I need, and the proper format I need to use.