john can type a set of pages in 5 hours at a constant rate . if john types for 3 hours and jack does the rest of the job , who works at 2 / 5 constant rate of john . how long will it take for jack alone to do the rest of the job ?
john will do 3 / 5 in 3 hrs , so john does 3 / 5 of the work . . therefore , jack will do the remaining 2 / 5 th work alone . . as the speed of jack is 2 / 5 rate of john , jack will do the 2 / 5 th work in same time that john takes to complete full job . . . ans 5 d
divide(multiply(const_1, divide(2, 5)), multiply(inverse(5), subtract(const_1, divide(3, 5))))