Questions

In scouts, the military and most outdoor books or schools teach the COLDER principal. It is a great acronym for caring and using you clothing.

C - keep your clothing CLEAN. Dirt can break down the fibers of your clothing.

O - don't OVERHEAT. Sweat can lessen the effectiveness of clothing.

L - wear you clothes LOOSE and in LAYERS. Makes your system versatile.

D - stay DRY.

E - EXAMINE your clothing. Look for worn or damaged areas of you clothing.

R - REPAIR any damage that is found.

Charles Macintosh (29 December 1766 – 25 July 1843) was a Scottish chemist and inventor of waterproof fabrics.He devoted all his spare time to science, particularly chemistry, and before he was twenty resigned his clerkship to take up the manufacture of chemicals. In this he was highly successful, inventing various new processes. His experiments with one of the by-products of tar, naphtha, led to his invention of waterproof fabrics.

The persons with 'O' blood group do not have antigens in the red corpuscles. So that blood will not cause agglutination of corpuscles if mixed with any type of blood. So group 'O' persons are called universal donors.

In each row, 

Sum of 1st two digit number + last two digit number = Middle two digit number

i.e., 1st row 15 + 40 = 55

2nd row 46 + 47 = 93

Similarly, 7x + 16 = 87 => x = 1.