function calculatePrice() {
var apples = fieldname11;
var pears = fieldname9;
var oranges = fieldname10;
var pineapples = fieldname12;

var totalFruits = apples + pears + oranges + pineapples;

var price = 0;

// Примерные цены на фрукты
var applePrice = 2;
var pearPrice = 3;
var orangePrice = 1.5;
var pineapplePrice = 5;

// Условие, при котором меняется общая стоимость
if (totalFruits <= 10) {
price = (applePrice * apples) + (pearPrice * pears) + (orangePrice * oranges) + (pineapplePrice * pineapples);
} else if (totalFruits <= 20) {
price = 0.9 * ((applePrice * apples) + (pearPrice * pears) + (orangePrice * oranges) + (pineapplePrice * pineapples)); // 10% скидка
} else {
price = 0.8 * ((applePrice * apples) + (pearPrice * pears) + (orangePrice * oranges) + (pineapplePrice * pineapples)); // 20% скидка
}

return price;
}