how can i combine 2 tables and including if clause into one column

I am pretty new in using SQL and trying to combine 2 tables within APEX ( interactive grid), based on the salary and rate the information to be taken from table X ( which i managed), but i need within the same SQL statement based on the information from column Type, to bring within column percentage if clauses to create the information.

and also within the same SQL statement to have the total which would be (ratehourspercentage).

but it seems i just cant manager to combine so many codes into one correctly, i have tried different ways based on what i have found examples all over, but it seems it will just not work for some reason.

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select 
Overtime.ID,
OVERTIME.EMPLOYEE_NUMBER,
OVERTIME.EMPLOYEE_FULL_NAME,
OVERTIME."DATE",
OVERTIME.TYPE,
OVERTIME.HOURS,
EMPLOYEES.RATE,
EMPLOYEES.SALARY,
OVERTIME.PERCENTAGE (CASE
WHEN TYPE = "On Call " THEN "70%"
WHEN TYPE = "On Call PH" THEN "100%"
ELSE "150%"
END),
(Rate*hours*percentage) as total,
OVERTIME.CREATED,
OVERTIME.CREATED_BY
from OVERTIME 
LEFT OUTER JOIN EMPLOYEES
ON OVERTIME.EMPLOYEE_NUMBER = EMPLOYEES.EMPLOYEE_NUMBER
group by Employee_Number

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select 
Overtime.ID,
OVERTIME.EMPLOYEE_NUMBER,
OVERTIME.EMPLOYEE_FULL_NAME,
OVERTIME."DATE",
OVERTIME.TYPE,
OVERTIME.HOURS,
EMPLOYEES.RATE,
EMPLOYEES.SALARY,
OVERTIME.PERCENTAGE,
(Rate*hours*percentage) as total,
OVERTIME.CREATED,
OVERTIME.CREATED_BY
from OVERTIME 
LEFT OUTER JOIN EMPLOYEES
ON OVERTIME.EMPLOYEE_NUMBER = EMPLOYEES.EMPLOYEE_NUMBER
WHERE OVERTIME.TYPE LIKE 
 (CASE
   WHEN TYPE = "On Call " THEN "70%"
   WHEN TYPE = "On Call PH" THEN "100%"
   ELSE "150%"
 END);
group by Employee_number

i need to have the percentage information to reflect within the percentage column which i presume should be with if clause