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

First step is to get rid of the square root. remember that a square root is the same as raising to the (1/2) power. see below: multiply exponents per exponent rules to get: remember you subtract exponents from the denominator and add exponents in the numerator so: simplify further: so a is the correct choice. if you don't understand this google exponent rules and it will you understand. look at the image results.