Both circle a and circle b have a central angle measuring 50°. the area of circle a's sector is 36π cm2, and the area of circle b's sector is 64π cm2. which is the ratio of the radius of circle a to the radius of circle b?

Expresa commuter train leaves downtown sation and travels at a average speed of 55 miles per hour towards the north side sation, which is 50miles away. thirty minutes later, express commuter train #7 leaves north side and travels at a average speed of 35miles per hour towards downtown sation. at the moment the two trains pass each other, how far(in miles) is train #12 from the downtown sation and how long(in minutes) has the #12 train been traveling