Quantitative Aptitude - Arithmetic Ability Questions

If 3a+4b3c+4d = 3a-4b3c-4d, then 

If the shopkeeper sells an item at Rs 1600 which is marked as Rs 2000, then what is the discount he is offering?

A bank offers 5% compound interest per half year. A customer deposits Rs 4800 each on 1st January and 1st July of a year. At the end of the year, the amount he would have gained by way of interest?

Length and breadth of a rectangle are increased by 40% and 70% respectively. What will be the percentage increase in the area of rectangle?

What is the value of {sin (90 – x) cos [π – (x – y)]} + {cos (90 – x) sin [π – (y – x)]}?

3cosA is equal to

If 2(5x - ­4) -­ 2 < 2x ­- 1 < 4x - ­2; then the value of x is

A shopkeeper sells wheat at a profit of 20% and for weighing uses a weight which is 10% less than the actual weight. What is his total profit percentage?