3(n+6) do i do 3xn=3n than 3x6=18 n=6?

Yes because it's the distributive property. The distributive property is where you multiply whatever is in the parentheses to the number on the outside. For instance, 5(20+11)  to answer this, you set it up like this: 5(_+_) this mean that there are two in the answer. So 5*20 equals 100 and 5*11 equals 55 so to set it up, you do 100+55. To see it the answer is right, you say 5(_+_) and like the factoring to find the numbe is the greatest common factor. The GCF of 100 and 55 is 5 so 100 divided by 5 equal 20 and 55 divided by 11 equals 5 so there you go.

A. d=rt --> r=d/t

B. r= 800000/4 = 200,000 m/h

C. r= 800/4 = 200 km/h

D. Kilometers. Since the distances are vast, it is better to use a more shorthand unit. Also, km/h is more commonly used. Meters are partnered with seconds (m/s)