Explanation

Let's calculate the total work hours:

195 men * 10 hours/day * 20 days = 39,000 man-hours

To finish the job in 15 days working 13 hours/day:

Let x be the number of men needed:

x men * 13 hours/day * 15 days = 39,000 man-hours

195 * 10 * 20 = x * 13 * 15

39,000 = 195x

x = 39,000 / 195

x = 200

The number of men is 200.

Explanation

The correct phrase is "We should not swim after a meal" as it's advised to wait before swimming.

"After" indicates the time following an event.

Explanation

Tuberculosis (TB) is primarily treated with a combination of antibiotics, which is a form of chemotherapy.

The treatment usually involves a prolonged course of multiple antibiotics to eliminate the bacteria.

Explanation

A teacher acts as a guide, helping students understand concepts, develop skills, and shape their character.

While teachers can also be role models, their primary role is to guide learning and personal development.

Explanation

The correct sentence is: People call this place the Forbidden Forest.

"Call" is used when naming or referring to something by a specific title.

Explanation

Let's check each pair in the equation:

2x + 3y = 24

{6, 4} → 2(6) + 3(4) = 12 + 12 = 24 ✓

{12, 0} → 2(12) + 3(0) = 24 + 0 = 24 ✓

{0, 8} → 2(0) + 3(8) = 0 + 24 = 24 ✓

{9, -2} → 2(9) + 3(-2) = 18 - 6 = 12 ✗

Explanation

Homework helps in developing discipline and study habits in students.

It encourages self-learning and independent practice, which are crucial for academic growth.

Explanation

In indirect speech, exclamation sentences are converted using "exclaimed" and a change of pronouns and verb tense.

The sentence "What a stupid fellow you are!" becomes "He exclaimed that what a stupid fellow I was."

Explanation

A set with no elements is commonly referred to as a null set, empty set, or void set.

All these terms mean the same: a set with zero elements, usually denoted by Ø or { }.

Explanation

The correct phrase is: "There is no substitute for hard work."

"Substitute" means a replacement, and the sentence implies hard work cannot be replaced.