christine and siri have 21 rs between them . christine has 20 rs more than siri . how much does christine have .
let siri has x rs , then christine has 20 + x rs given x + ( 20 + x ) = 21 = > 2 x = 1 or x = 0.5 so christine and siri has 20.5 and 0.5 rs respectively . answer : e
add(divide(subtract(21, 20), const_2), 20)