function petshopExpenses(input) {
    let ourDogsExs = parseFloat(input.shift() * 2.50);
    let neighboursDogsExs = parseFloat(input.shift() * 4.00);
    let expenses = (ourDogsExs + neighboursDogsExs).toFixed(2);
    console.log(`${expenses} lv.`)
}
petshopExpenses( [
    13,
    9,
] )