Tutor profile: Matt O.

There are 85 cards in a box. Andre has 13 cards in a bag. Alan takes 30 cards out of the box. How many cards are left in the box?

There is some unnecessary information in the question here. Andre and the cards in his bag can be a distraction. We only need to use the number of cards in the box and the number taken out. 85 - 30 = 55

Solve 5x - 20 = 35

We solve by using the same operation on both sides of the equals sign to strategically isolate the x. We can start by adding 20 to both sides of the equation. 5x = 55 Then we can divide by 5 x = 11 Now that x is isolated we have solved the equation. We could even substitute it back into the equation to verify that it works as a solution. 5(11) - 20 = 55 - 20 = 35

How do I know whether to find a critical region or calculate a probability to complete a hypothesis test?

The p-value is only able to be used/calculated if you have an observed value in the question. The critical region can be calculated whether you are given an observed value or not.