a is two years older than b who is twice as old as c . if the total of the ages of a , b and c be 47 , the how old is b ?
"let c ' s age be x years . then , b ' s age = 2 x years . a ' s age = ( 2 x + 2 ) years . ( 2 x + 2 ) + 2 x + x = 47 5 x = 45 x = 9 . hence , b ' s age = 2 x = 19 years . d )"
divide(multiply(subtract(47, const_2), const_2), add(const_4, const_1))