If 5 engines consume 6 metric tonnes of coal when each is running 9 hours a day, how much coal will be needed for 8 engines, each running 10 hours a day, it being given that 3 engines of the former type consume as much as 4 engines of the latter type ??

(a) 8

(b) 3 + 1/8

(c) 6.48

(d) 8 + 5/9