What instrument is used to measure air

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

(40/25) X 80 - ? = 45% of 300 - 55

√(2670+ √(1141+ √(260- √(1251- √(637+ √1521) ) ) ) )  =?

22% of 560 + 34% of 2160 × 5/12 =? + 16% of 920

√? + √1296 + √729 = 464/4  

62.94%  of  1800 - 15.03 %  of  2400 = ?  

464 + 181 +? = (154 × 25) - (15) ²  

√1369 + √1024 + √841 =(?)² − 46 

625 × (?% ÷ 125) = 250% of 10

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

9 ^{(? + 12)} = 3 ^{(14 + 17 - 11)}

(512) ^(2/3) × √64 ÷ (512) ^(1/3) = (64) ^(?/2) ÷ (2)⁶