function petshop(input) {
    let ourDogs = input.shift();
    let theirDogs = input.shift();
    let ourDogsExpenses = ourDogs * 2.50;
    let theirDogsExpenses = theirDogs * 4.00;
    let totalExpenses = (ourDogsExpenses + theirDogsExpenses).toFixed(2);
    console.log(totalExpenses);
    console.log(typeof totalExpenses);
}
petshop( [
    5,
    4,
] )