Questions

The resistance of metallic conductors e.g, platinum, increases with rise of  temperature . The increase in temperature results in a decrease of current which can be recorded in a galvanometer if the conductor is included in an electrical circuit. Thus the temperature can be known; platinum resistance thermometer is used generally for accurate scientific work. When two dissimilar metals are joined at the ends, and these ends are subjected to a difference of temperature, a current flows through the metals. Greater the difference of temperature , greater the current. So the curent strength can form the basis for measuring the difference in temperature. And when one of these temperatures is known, we can calculate the other.

Now a days, printers we are using are called as laser printers. The speed of a laser printer is measured in PPM i.e, Pages Per Minute. 

Laser printing is an electrostatic digital printing process. It produces high-quality text and graphics by repeatedly passing a laser beam back and forth over a negatively charged cylinder called a "drum" to define a differentially charged image.

Compared to inkjet printers which use ink for printing laser printers are more expensive as they use toner which lasts for long.

Let the given be resembled in letters like R, G & B.

Here given,

1) R + R + R = 30

=> 3R = 30 => R = 30/3 = 10

2) R + G + G = 18 => R + 2G = 18 => 10 + 2G = 18 => 2G = 8 => G = 4

3) G - B = 2 => B = G - 2 => B = 4 - 2 => B = 2

Hence, R + G + B = 10 + 4 + 2 => 16.