In a survey of mobile and telephone, it was found that 200 people had telephone, 25 had both, 135 did not have telephone and 300 did not have mobile.
i. How many people participated in the survey?
ii. How many people had mobile only

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