If a:b=3:5 and b:c=7:8 ,then 2a:3b:7c is equal to

If m persons can paint a house in d days,how many days will it take for (m+2) persons to paint the same house?

By increasing the speed of his car by 15 km/hr,a person covers 300km distance by taking an hour less than before.The original speed of the car was

If 4 men working 4 hours per day for 4 days complete 4 units of work,then how many units of work will be completed by 2 men working for 2 hours per day in 2 days?

A motor boat whose speed is 15km/hr in still water goes 30km downstream and comes back in a total of 4hr and 30 minutes.The speed of the stream is

If the roots of the quadratic equation x²-4x-log N=0 are all real,then the minimum value of N is