Which two signs should be interchanged to make the following equation correct?
20 ÷ 20 + 20 – 25 × 25=419

The sum of the present ages of two cousins is 46 years. Eight year ago, the elder one was twice as old a the younger one. What is the present age of the elder cousin?

If 5=10, 6=18, 7=28 then 8=?

Which interchange of signs will make the following equation correct?
35 + 7 * 5 ÷ 5 - 6 = 24

A man is 3 years older than his wife and four times as old as his son. If the son becomes 15 years old after 3 years, what is the present age of the wife? 

Ashok's mother was 3 times as old as Ashok 5 years ago. After 5 years she will be twice as old as Ashok. How old is Ashok today? 

In the following question, by using which mathematical operators will the expression become correct?
30 ? 6 ? 4 ? 5 ? 4

If "P" denotes "multiplied by", "R" denotes "subtracted from", "S" denotes "added to" and "Q" denotes "divided by", then which of the following equation is true?