Question

goods sold for cash costing rs 10000 and on credit costing 15000 both at a profit of 20%

Answer 1

cash sales = 10000+20%(10000)
                  =12000
 
Credit sales  =15000+20%(15000)
                     =15000+3000
                       =18000

Journal entry 

cash A/c    Dr   12000
Debtor A/c   Dr  18000
      To sales A/c                 30000
(being sales made )

Hope its useful ..!!