Mathematical Operations Questions

If 25 + 5 ÷ 2 = 40 , and 35 + 5 ÷ 2 = 60 , then 45 + 5 ÷ 2 = ?

The following equation is incorrect. Which two signs should be interchanged to correct the equation? 15 x 12 + 40 ÷ 40 - 6 = 21

If "–" means "added to", "+" means "divided by", "÷" means "multiplied by", "x" means "subtracted from", then 13 + 12 x 9 ÷ 3 – 6 = ?

In the following question, correct the equation by interchanging the two signs.
6 ÷ 17 x 51 + 6 – 12 = – 4

If "–" means "divided by", "+" means "multiplied by", "÷" means "added to", "x" means "subtracted from", then 11 ÷ 6 – 2 + 5 x 3 = ?

Select the missing number in the given question?

In the following question, by using which mathematical operator will the expression become correct?
18 ? 6 ? 9 ? 27

Find the missing number?