on a certain planet where people usually tend to live for more than a century , the ratio of present ages of father and son is 7 : 4 . 10 years later , the ratio of their ages will be 5 : 3 . what is the sum of their present ages ?
the ratio of present ages of father and son is 7 : 4 , so suppose the present ages are 7 x and 4 x , respectively . 10 years later , the ages of father and son , respectively , shall be 7 x + 10 and 4 x + 10 . the ratio of ages 10 years later is given to be 5 : 3 . this means ( 7 x + 10 ) / ( 4 x + 10 ) = 5 / 3 solving we get x = 20 . so present age of father is 7 x = 140 and present age of son is 4 x = 80 . the sum of present ages is thus 220 . ans a
add(multiply(7, subtract(multiply(5, 10), multiply(3, 10))), multiply(4, subtract(multiply(5, 10), multiply(3, 10))))