Problem: what is rate of interest if principal . amount be 400 , simple interest 80 and time 2 year .
Rationale: "s . i = ( p * r * t ) / 100 80 = 800 r / 100 r = 80 / 8 = 10 % answer a"
annotated_formula: multiply(divide(80, multiply(400, 2)), const_100)