If 40% of a number is equal to 3 / 5th of another number, what will be the ratio of the first number and the second number?

Direction : What value should come in the place of question mark (?) in the following questions?

3.6 + 36.6 +3.66+0.36+3.0=?

Thrice the square of a natural number decreased by four times the number is equal to 50 more than the number. The number is :

The arithmetic mean of the following data is .

23, 17,20,19,21

Of the three numbers, the sum of the first two is 55, sum of the second and third is 65 and sum of third with thrice of the first is 110. The third number is: 

What is the sum of all three-digit numbers which are divisible by 20?

The digit in the unit's place of the number represented by (7⁹⁵ - 3⁵⁸) is: 

When the integer n is divided by 7, the remainder is 3. What is the remainder if 5n divided by 7?