15 + Minutes

function Time(input){
    let starthour = Number(input.shift());
    let startminutes = Number(input.shift());

    let timeinminutes = starthour * 60 + startminutes;
    //startminutes += starthour * 60
    // startminutes += 15;

    let timeplus15 = timeinminutes + 15;
    let finalhour = Math.floor(timeplus15 / 60);
    let finalminutes = timeplus15 % 60;

    if( finalhour >= 24){
        finalhour -=24;
    }
    if (finalminutes < 10) {
        console.log(`${finalhour}:0${finalminutes}`);
    } else {
        console.log(`${finalhour}:${finalminutes}`);
    }
}
Time(["1","46"]);