Which gases contribute primarily to the formation of

The value of ((0.27)²-(0.13)²) / (0.27 + 0.13) is:

(117 + 93 - 10) ÷ 40 = ? - 12 X 2

(8.6 × 8.6 + 4.8 × 4.8 + 17.2 × 4.8) ÷ (8.6² – 4.8² ) = ? ÷ 19

800 + 900 X (3)^-2 - ? = 25 X 60 ÷ 2 

12.5% of 45 % of 480 + 957/29 = ? -14 × 15

7(1/7)% of 3500 + 6(2/3) % of 6000 = ? + 552.5

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

? = (20 × 62 – 34² )

((9.77)⁰- 〖(0.1)〗^(-1))/(〖(6/2⁴ )〗^(-1) ×(3/2)³+ 〖((-2)/6)〗^(-1) ) = ?

5³ – 8 = ? + 126