If in a certain code language, '12 - 3' means 36, '21 + 3' means 7, '17 × 2' means 19, and '15 ÷ 3' means 12, then find the value of the following expression: 144 ÷ 315 + 35 × 16 - 17 = ?

If: 'A % B' means 'A is multiplied by B', 'A # B' means 'A is added to B', 'A @ B' means 'A is divided by B', and 'A $ B' means 'B is subtracted from A'; then what is the value of 15 @ 5 % 7 # 9 $ 4?

Which two numbers should be interchanged to make the given equation correct? 98 ÷ 3 + 25 × 7 - 18 = 71