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

A father was twelve times as old as his son twenty years ago. Now he is twice as old as his son. What are the present ages of the son and father?

In the following question, two signs and two numbers need to be interchanged to make it correct. Select the appropriate signs and number from the given alternatives.
6 × 8 + 2 = 20

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

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 is 5 times as old as his son. His son is 6 years old. His son is 6 years old. After how many years, will the father be 4 times as old as his son?

Which two signs need to be interchanged to make the following equation correct?
45 – 9 ÷ 3 +5 ×6 =32

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.