Which among the following is the oldest mountain range

1231 + 1312 + 2113 – 3211 = ?

Determine the value of ‘a’ if a = √529 + √1444

[192 ÷ 6 × 5] ÷ (? + 3) = 20 

[(120)² ÷24 ×25] ÷ 250 =?

What will come in the place of question mark (?) in the given expression?

(252 + 198) ÷ ? + 126 ÷ 3 = 144 ÷ 2

What value should come in the place of (?) in the following questions?

70% of 240 + 75% of ? = 45 * 55 ÷ 5

Ravi is 12 years younger than Surya. Ravi's age is 40% of the sum of his and Surya's age. What will be Surya's age 9 years hence? 

What will come in the place of question mark (?) in the given expression?

√64 X 9 ÷ 3 + 12 X 3 = ? + 36

55% of ? = 45 + 20 × 6