Round 296,386,482 to nearest million

Can someone me with the property questions for 12 13 and 14 plz

Two trains leave stations 546 miles apart at the same time and travel toward each other. one train travels at 95 miles per hour while the other travels at 115 miles per hour l. how long will it take for the two trains to meet

Which is an equivalent equation solved for r? the circumference of a circle can be found using the formula c = 2πr. r=cπ r=c(2π) r= c over 2π r= 2π over c