Function in Oracle Sql

Question

How do I perform these if Else in SQL

create or replace function inss(x real)
return number is
begin 
    if x <= 840.55 then 
        return ((7.65/100) * x);
    else if (x >= 840.56) and (x <= 1050.00) then 
        return ((8.65/100) * x);
    else if (x >= 1050.01) and (x <= 1400.91) then 
        return ((9/100) * x);
    else if (x >= 1400.92) and (x <= 2801.82) then 
        return ((11/100) * x);
    else 
        return 308.20;
    end if;
end;

You’re making that mistake

Errors: FUNCTION INSS Line/Col: 15/4 PLS-00103: Encountered the Symbol ";" when expecting one of the following:

if