计算给定数字到两个给定数字之间的百分比

Question

I'm trying to work out a percentage between two numbers by providing the number of which the percentage should be based (can't find this on Stack overflow - only percentage between two numbers).

Let me explain:

$start_number = 14700
$end_number = 14900


// This is the number to calculate a percentage for
// in this basic example this should come to 50%
$percentage_number = 14800

I know what I need to do but can't figure out how to write it:

Where $start_number is 0%

And $end_number is 100%

$percentage_number = X%

Answer 1

$difference = $end_number - $start_number; // 200
$difference_from_start = $end_number - $percentage_number; // 100
$percentage = $difference_from_start / $difference; // 0.5 (50%) 

Is it what you want?