If “P” denotes “divided by”, “R” denotes “added to”, “S” denotes “subtracted from” and “Q” denotes “multiplied by”, then
48 P 4 R 3 Q 4 S 6 Q 4 = ?

The weights of 4 boxes are 70, 100, 20 and 40 kilograms. Which of the following cannot be the total weight, in kilograms, of any combination of these boxes and in a combination a box can be used only once. 

Which two numbers should be interchanged to make the following equation correct?
7 – 8 ÷ 4 + 5 × 3 = 8 × 3 + 6 ÷ 2 – 3

The total age of a mother and her son is 60 years. The difference between their ages is 30 years. Find out the age of the mother.

In the following question, correct the equation by interchanging two numbers.
9 × 3 – 8 ÷ 2 + 7 = 26

Which two signs should be interchanged to make two given equation correct.
4 × 8 ÷ 16 – 4 + 6 – 3 + 2 = 32

In a string of 20 beads, the average weight of the first 14 beads is 25 grams and that of the last 6 beads is 8 grams. What is the average weight of all the beads?

If -4$1 = 4, 7$-7 = 49 and 3$1 = -3, then find the value of -8$-5 = ?