How can I add an if else conditional statement to this function?

How can a modify this function so if the user enters less than 2500 cubic ft the price is equal to 0?

function updateCombustibleMaterialFireFee(cubicft) {
var price = 42;
if (cubicft > 5000) {
    price += (cubicft-5000)/1000*22;
} 

// Change the parameters to the correct fee code, fee schedule, etc.
// updateFee(fcode, fsched, fperiod, fqty, finvoice, pDuplicate, pFeeSeq)
updateFee("FPERMIT47","FIRE","FINAL",price,"N","N");

logDebug("$" + price);

}