Quantitative Aptitude - Arithmetic Ability Questions

20% discount is offered on an item. By applying a promo code the customer wins 10% cash back. What is the effective discount?

Mahanath works 2 times as fast as Sahay. If Sahay can complete a job alone in 21 days, then in how many days can they together finish the job?

Sumit is 28% less efficient than Amit. If Amit can make a wall in 54 days, then Sumit can complete the same work in how many days?

A batsman makes a score of 95 runs in the 13th match and thus increases his average runs per match by 4. What is his average after the 13th match?

The marked price of a trouser is twice of the cost price. To earn 36% profit, what should be the value of discount (in percentage)?

In each of the following questions two equations I and II are given. Solve both the equations and give answer:
$$\begin{gathered} I. x2+2x-195=0 \\ II. y2+30y+225=0 \end{gathered}$$

The area of a circle is 616 sq cm, find its circumference?

What is the value of tan4A + tan2A?