Problem: the c . p of 20 books is equal to the s . p of 30 books . find his gain % or loss % ?
Rationale: explanation : 20 cp = 30 sp 30 - - - 10 cp loss 100 - - - ? = > 33.33 % loss answer : c
annotated_formula: multiply(subtract(const_1, divide(20, 30)), const_100)