S, T and U together can complete a work in 30 days. If the ratio of efficiency of S, T and U is 20 : 15 : 12 respectively, then in how many days U alone can complete the same work?
A and B together do a job in 6.75 days and A could do the job in 9 days if he worked alone. How many days would B take to do the job if he worked alone?
A can paint a house in 42 days and B can do it in 21 days. Along with C, they can finish the job in 7 days only.C alone can do the painting job in how many days, ?