If "–" stands for division, "+" stands for multiplication, "÷" stands for subtraction and "×" stands for addition, which of the following equations is correct?

Some equations are solved on the basis of a certain system. Find out the correct answer for the unsolved equation on that basis.
If 8 + 8 = 72, 5+5 = 30 and 7+7=56, what is 6+6 =?

A father's age was 8 times his son's age 4 years ago. Presently the father's age is 4 times that of his son. Find the present age of the son?

If “+” denotes ‘ – ‘ , ‘ – ‘ denotes ‘× ‘, ‘×’ denotes ‘÷’  and ‘÷’ denotes ‘+’, then what is the value of
15 – 5 +15 ÷ 45 × 15

The sum of the ages of a father and his son is 56 years. After 4 years, the father's age will be 3 times his son's age. Their ages are respectively.

Which two signs should be interchanged to make the following equation correct?
5 + 3 x 8 - 12 ÷ 4 = 3 

The ratio of the present age of the two brothers is 1: 2. And 5 years ago this ratio was 1: 3. So what will be the ratio of their age after 5 years.

If ‘÷’ means ‘+’; ‘ –‘ means ‘x’; ‘x’ means ‘÷’ and ‘+’ means ‘ –‘; then 111 – 21 ÷ 7 × 2 + 4 – 127=?