Can’t find the way to calculate and output it

I’m trying to get the percentage from the “timeSpend” and “breakTime” and store in fSubject,sSubject, tSubject and store it in dataset: date[],
so that it can output it but it just gives the value of “timeSpend” and “breakTime” not fSubject,sSubject, tSubject enter image description here

 let timeSpend = document.querySelector("#time_spend").value;
let breakTime = document.querySelector("#break_time").value;
let fSubject = document.querySelector("#first_subjects").value;
let sSubject = document.querySelector("#second_subjects").value;
let tSubject = document.querySelector("#third_subjects").value;

let fSubjectV = (50/100) * (timeSpend + breakTime); 
let sSubjectV = (25/100)* (timeSpend + breakTime);
let tSubjectV = (25/100)* (timeSpend + breakTime);

let myChart = document.getElementById("myChart").getContext("2d");

document.querySelector("button").addEventListener("click", () => {
    let pieChart = new Chart(myChart, {
        type: "pie",
        data: {
            labels: [
                "Time spend",
                "Break Time",
                "First Subject",
                "Second Subject",
                "Third Subject",
            ],
            datasets: [
                {
                    label: "Plan",
                    data: [
                        timeSpend.value,
                        breakTime.value,
                        fSubjectV.value,
                        sSubjectV.value,
                        tSubjectV.value,
                    ],
                },
            ],
        },
        options: {},
    });
});