php calculator switching multiplier based on input - php

Question

Hello I am building a simple computer in php.
It should work in the way that when the user selects number greater than 30, the variable ( in this case m1 ) becomes m2 and so on.
How can i accomplish this?
Thank you in advance
<?php
$m1 = 5 /*prezzo della maglia - price 1*/;
$m2 = 2;/*price when quantity is over a number*/
$m3 = 1;/*price when quantity is over a number*/
$s1 = 3; /*price of print 1*/
$s1 = 3; /*price of print 1 if quantity change*/
$bxs = $_GET['bxs'];
$bs = $_GET['bs'];
$bm = $_GET['bm'];
$bl = $_GET['bl'];
$bxl = $_GET['bxl'];
$b2xl = $_GET['b2xl'];
/*riga del nero*/
$nxs = $_GET['nxs'];
$ns = $_GET['ns'];
$nm = $_GET['nm'];
$nl = $_GET['nl'];
$nxl = $_GET['nxl'];
$n2xl = $_GET['n2xl'];
$somma = $m1*($bxs+$bs+$bm+$bl+$bxl+$b2xl+$nxs+$ns+$nm+$nl+$nxl+$n2xl);
?>

Answer 1

It is simple, but you must provide the user way enter that value.
For example by the GET parameter number
$userInput = $_GET['number'];
Then you only need to create basic if statement. You can read about it at http://php.net/manual/en/control-structures.if.php
$somma = $bxs+$bs+$bm+$bl+$bxl+$b2xl+$nxs+$ns+$nm+$nl+$nxl+$n2xl;
if($userInput <= 30){
$somma *=$m1;
}else if($userInput >30) {
$somma *=$m2;
} else if($userInput > 8779){ // your number : )
$somma *=$m3;
}