Please Help Me,

Whats the easiest and most simplest way to understand and work out this solution. Please show any shortcuts. Thanks

A.Ben sails 1/3 of his trip at 4km/h, the next 1/3 at 8 km/h and the last 1/3 at 6 km/h. The trip takes him 9 hours and 45 minutes. How far was the complete trip ?

B.In a zoo there are 17 more monkeys than lions and 30 more lizards than lions. If there were 151 animals in total, how many of each animal are there ?

Thanks