Your mother is 4 years younger than your father and your father is 6 times older than you. If you are 6 years old, what is your mother's age?

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

Identify the symbols to be inserted to make the expression correct.
24 Δ 4 Δ 5 Δ 4

Select the correct set of symbols:
34  16  4  12  = 26

If P means -, Q means +, R means x and  S means ÷ then what is the value of  8 R6S3Q5P9 

If ‘+’ means ‘-‘; ‘-‘ means ‘×’; ‘×’ means ‘÷’ and ‘÷’ means ‘+’, then
25×5÷30+8 – 2 =?

If 16 Δ 4= 64 and 216 @ 8=27 and what is the value of 8 Δ 5@ 4 =?

The ratio of the number of girls to the number of boys in a town is 90 %. If the total number of boys and girls in the town is 190, how many girls are in the town?