Show amount for 3, 6 and 12 installments, under regular price

mx_price_per_installments.php

add_action( 'woocommerce_single_product_summary', 'mx_price_per_installments', 11 );

function mx_price_per_installments() {

    global $product;
    $price = $product->get_price();
    $threeinstallments = 3;
    $sixinstallments = 6;
    $twelveinstallments = 12;

    $price_per_threemonths = round ($price / $threeinstallments , wc_get_price_decimals(), PHP_ROUND_HALF_DOWN);
    $price_per_sixmonths = round ($price / $sixinstallments , wc_get_price_decimals(), PHP_ROUND_HALF_DOWN);
    $price_per_twelvemonths = round ($price / $twelveinstallments , wc_get_price_decimals(), PHP_ROUND_HALF_DOWN);
    
    echo "
    <div id='installments-container'>
        <div id='installments-text'>
	Obročno plaćanje: 3 x <span>". $price_per_threemonths ." Kn</span> | 6 x <span>". $price_per_sixmonths ." Kn</span> | 12x <span>". $price_per_twelvemonths ." Kn</span>
        </div>
    </div>
    ";
}