Questions

Any of the basic mechanical devices for applying a force are called simple machines.

There are 6 basic simple machines; the lever, the wheel and axle, the inclined plane, the wedge, the pulley, and the screw. Several of these simple machines are related to each other. But, each has a specific purpose in the world of doing work.

Controlled railroad crossing includes warning signs, red lights and railway gates, whereas absence of all of these warning signs like red lights and gates includes uncontrolled railroad crossings. 

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.

Makthabs taught the primary education to muslims during the period of sultanate

Let the required weight be x kg.

Less weight, Less cost (Direct Proportion)

 250 : 200 :: 60 : x   =>    250 x x = (200 x 60)

=>

=> x = 48.

Office salaries expense would not come under a selling expense.