I think the answer is B but i could be wrong
Answer:
3
Step-by-step explanation:
15 minus 9 equals 6. 6 divided by 2 equals 3.
Um... it'll take each pipe 80 mins, bcz if together they take that long, then to find the pipes time separately, you just multiply it by two to show it doing the work the other pipe did as well. Is that what you wanted??
Answer: speed is 540 km/h
Step-by-step explanation: Lets mark speed as v.
Because distenace is same, you can mark 6 h · 900 km/h = 10 h · v
and v = 5400 km / 10 h = 540 km/h.
Or using inverse proportions : 10 h / 6 h = v / 900 km/h .
Before multiplying you turn lastproportion around :
10 h / 6 h = 600 km/ h / v ,which gives 10 v = 6 · 900 km/h
and result is same