It would be a lot easier to understand if you had some HTML code of the layout.
This is only a guess, but you might be able to modify it to your needs.
I turned āPaul_Wilkinsā answer into a function rather than direct execution
and I abbreviated you array names because I am such a poor typist ā¦
The code might be compressed further with more comprehensive understanding of your needs.
See if this of any help. 
<!DOCTYPE html><html lang="en"><head><title> Array Additions </title>
<meta charset="UTF-8">
<meta name="viewport" content="width-device-width,initial-scale=1.0, user-scalable=yes"/>
<!-- From: https://www.sitepoint.com/community/t/how-do-i-add-button-values-when-the-buttons-have-an-array-of-values/351566/5 -->
<style>
html { box-sizing: border-box; }
*, *:before, *:after { box-sizing: inherit; }
fieldset { display: flex; flex-wrap: wrap; }
span { flex: 1 0 25%; }
</style>
</head><body>
<fieldset> <legend>Addition</legend>
<span><button onclick="msg('btn0', answers(a, b))">Answers</button> <pre id="btn0"></pre></span>
<span><button onclick="msg('btn1', answers(b, c))">Answers</button> <pre id="btn1"></pre></span>
<span><button onclick="msg('btn2', answers(c, d))">Answers</button> <pre id="btn2"></pre></span>
<span><button onclick="msg('btn3', answers(d, e))">Answers</button> <pre id="btn3"></pre></span>
<span><button onclick="msg('btn4', answers(a, c))">Answers</button> <pre id="btn4"></pre></span>
<span><button onclick="msg('btn5', answers(b, d))">Answers</button> <pre id="btn5"></pre></span>
<span><button onclick="msg('btn6', answers(c, e))">Answers</button> <pre id="btn6"></pre></span>
<span><button onclick="msg('btn7', answers(d, a))">Answers</button> <pre id="btn7"></pre></span>
</fieldset>
<script>
const doc = (IDS) => document.getElementById(IDS);
const msg = (IDS, ...message) => doc(IDS).innerHTML += message.join(' ');
console.clear();
a = ["1", "0", "-0.7", "0"];
b = ["1", "0.5", "-0.7", "0.35"];
c = ["2", "0.5", "-1.4", "0.35"];
d = ["3", "1", "-2.1", "0.7"];
e = ["6", "1.5", "-3.5", "1.05"];
function answers(a,b) {
var result = a.map(function addTogether(aItem, index) {
const bItem = b[index];
return (Number(aItem) + Number(bItem)).toFixed(2);
});
return `${[...a]} \n${[...b]} \n${[...result]}`;
}
</script>
</body></html>