how do i make this in mta?

[yesyesok]

$from = "USD"; 
$to = "GBP"; 
$amount = 12.50; 
$url = "http://www.exchangerate-api.com/".$from."/".$to."/".$amount."?k=API_KEY"; 
$result = file_get_contents($url); 
echo $result; 

i was learning php for Mta, what should i do to make it like a command

/currency usd gbp and it outputs the result.

[WhoAmI]

Use

callRemote 

to connect MTA with website.

[ALw7sH]

or

fetchRemote 

if you want to get what you did echo for

[Walid]

function convertMoney(plr, cmd, usd, gbp, amount) 
    if plr and isElement(plr) then  
        if not (tostring(usd)) or not(tostring(gbp)) then 
            outputChatBox("[Wrong Command]: /currency usd gbp ", plr, 0, 255, 0) 
        return 
    end 
    if (not tonumber(amount)) then return end 
    exchangerate(plr,usd,gbp,amount) 
    end 
end  
addCommandHandler("currency", convertMoney) 
  
function currency_return(sum) 
    if sum ~= "ERROR" then 
        outputChatBox(sum) 
    end 
end 
  
function exchangerate(player,usd,gbp,amount) 
    if (usd and gbp and amount) then 
       return callRemote("<< you php file link >>", currency_return, player, usd,gbp,amount) 
    end 
end 

untested

Note: as ALw7sH said you must use fetchRemote to get echo (print text) or try to change you php file code.