I have created a instant taxi quote calculator, the function below is the code that is used to calculate the fare from the distance. The problem is i've got my self confused about the maths in particular the < and >. If you do the maths on an normal calculator with the distance as 1.08, the fare should be 2.34

Code:
distance = 1.08
distance - 1 = 0.08
0.08 * 1.80(PPM) = 0.144
0.144 + 2.20(FirstMile) = 2.344
fare = 2.34
When you run the fare calculator it calculates the fare at: 3.24, when i comment out the if statements and have the FirstMile at 2.20 and PPM at 1.80 it works as it should.

Thanks in advance, Chris1990

Code:
function calcFare() {
// variables
	var fareResult;
	var distance = document.getElementById('txtDistance').value;
 	var firstMile;// = 2.20;// 2.20 for 1st mile
	var pricepMile;// = 1.80;// 1.80 per mile
	var TrafficP;// = 1.00;// add 15% for traffic
 //	Select Tarrif

	if (distance > 15); // less than 15 Mile
	{firstMile = 2.20; // FM £2.20
	TrafficP = 1.00;// add 00% for traffic
	pricepMile = 1.80};// PPM £1.80 - standard tariff
	
	if (distance > 30); //less than 30 Mile
	{firstMile = 3.00; // FM £2.50
	TrafficP = 1.00;// add 15% for traffic
	pricepMile = 1.40};// PPM £1.40

 	if (distance > 50); // less than 50 Mile
	{firstMile = 3.00; // FM £3.00
	TrafficP = 1.00;// add 10% for traffic
	pricepMile = 1.30;}// PPM £1.30
	
	if (distance > 100); // less than 100 Mile
	{firstMile = 3.00; // FM £3.00
	TrafficP = 1.00;// add 10% for traffic
	pricepMile = 1.20;}// PPM £1.20
	
 	if (distance > 175); // less than 250 Mile
	{firstMile = 3.00; // FM £3.00
	TrafficP = 1.00;// add 10% for traffic
	pricepMile = 1.15;}// PPM £1.10
	
 	if (distance > 300); // less than 500 Mile
	{firstMile = 3.00; // FM £3.00
	TrafficP = 1.05;// add 10% for traffic
	pricepMile = 1.10;}// PPM £1.00
/*	
 	if (distance > 60); // Over 50 Mile
	{firstMile = 3.50; // FM £3.50
	TrafficP = 1.10;// add 10% for traffic
	pricepMile = 1.20;}// PPM £1.20
*/
  // calculator for Car
  		//exc 1st mile and calc rest of miles by PPM
  	fareResult = (distance - 1) * pricepMile
  		//inc first mile
  	fareResult = fareResult + firstMile;
  	//add percent for traffic
    fareResult = fareResult * TrafficP;	
  // show fare result
	var roundedNumber = roundNumber(fareResult,2);
		if (roundedNumber < 1.675) {roundedNumber = "1.70"};	
	document.getElementById('txtFare').value = roundedNumber;
	calcType();
	document.getElementById('btnBookNow').style.visibility='visible'; // show booknow button 
	}