Plz me i really don't understand what this is talking about

All you gotta do...
is divide 400 by 7 to make 7 hours become 1 hour!

400/7 is about 57.
Round 57 to the nearest tenth!

That's 60 because 7 is the nearest number to next 0.
Choice: C

If the Garibaldi family drove 400 miles in 7 hours.Which is the best estimate of the number of miles they droove in 1 hour? A.40 miles,B.50 miles C.60 miles D.70 miles.. Try Multiplying each answer by 7 and see what your answer will be...For example: 7 x 50 = 350 its close too 400. so go down the line and figure out with one is closer to 400 miles.. My answer is C.60 miles which 420 miles so therefor it is only 20 miles more than 400 so its closer than A,B,or D

Assuming this is the book one the answer is rectangular prism.