Nicholas's sand castle is 30 cm tall and he is adding sand at a rate of 12 cm per minute. Nina's sand castle is 78 cm tall and she is adding more sand to it at a rate of 6 cm per minute. After how many minutes, x, will Nina and Nicholas's sand castles be the same height?

8 minutes

Step-by-step explanation:

Speed or Rate = Distance / time

Distance = Speed × time

Nicholas's sand castle is 30 cm tall and he is adding sand at a rate of 12 cm per minute.

Nicholas = Nina

30cm + (12cm/min)x

= 30 + 12x

Nina's sand castle is 78 cm tall and she is adding more sand to it at a rate of 6 cm per minute.

78cm + (6cm/min)x

78 + 6x

30 + 12x = 78 + 6x

12x - 6x = 78 - 30

6x = 48

x = 48/6

x = 8 minutes

Therefore, after 8 minutes, Nina and Nicholas's sand castles be the same height.

i believe the correct answer is option 4.principalities were small territories that were run by russian rulers.

which statement correctly defines principalities in northern asia in the 1200s? principalities were small territories that were run by russian rulers.

hope i could ! : )

a is 8.b is 10.c is 10.5. d is -.5

step-by-step explanation:

just minus the smallest number from the biggest.