Calculate: $−5 \times 5 − (−8) \times 2$

1 The sum of the reciprocals of the ages of two colleagues is five times the difference of the reciprocals of their ages. If the ratio of the products of their ages to the sum of their ages is 14.4 : 1, the age (in years) of one of the colleagues must 2 A liquid 'P' is $1\frac{3}{7}$ times as heavy as water and water is $1\frac{2}{5}$ times as heavy as another liquid 'Q' The amount of liquid ‘P' that must be added to 7 litres of the liquid ‘Q' so that the mixture may weigh as much as an equal volume of w 3 The average weight of 40 passengers in a bus is 58 kg. When the weight of the driver, conductor and their two helpers is included, the average weight increased by 2 kg. When the weight of the bus is also included, the average weight becomes 7 times the av 4 Three measuring rods are of length 120 cm, 100 cm and 150 cm. Find the least length of the fence that can be measure an exact number of times, using any of the rods. How many times each rod will be used to measure the length of the fence? 5 Three friends plan to go for a morning walk. They step off together and their steps measures 48 cm, 52 cm and 56 cm respectively. What is the minimum distance each should walk so that each can cover the same distance in complete steps ten times?