Question

Complete the sentences below by filling in the blanks.

Two trains are moving towards each other along a straight line. To find the speed of one train relative to the other train, you need to __________ their speeds.
Two trains are moving forwards in the same direction along a straight line. To find the speed of one train relative to the other train , you need to __________ their speeds.

Answer 1

1. you need to increase their speeds
2. you need to decrease their speeds