Answer
2p+12b=12
Step-by step explanation
I used p for plates and b for bowls\
2p+12b=4+(4*2)
2p+12b=12
 
        
                    
             
        
        
        
Answer:

Step-by-step explanation:
Let's write out a case for two specific questions being correct and the rest being incorrect:
 ,
,
The  represents the chances of getting the question correct, as there are 5 answers and 1 correct answer choice.
 represents the chances of getting the question correct, as there are 5 answers and 1 correct answer choice.
The  represents the chances of getting the question incorrect, as there are 5 answers and 4 incorrect answer choices.
 represents the chances of getting the question incorrect, as there are 5 answers and 4 incorrect answer choices.
The equation above does show the student getting two answers correct and three answers incorrect, but it only shows one possible case of doing so.
We can choose any two of the five questions to be the ones the student gets correct. Therefore, we need to multiply this equation by the number ways we can choose 2 from 5 (order doesn't matter):  .
.
Therefore, the probability the student gets two questions correct is:

 
        
             
        
        
        
This simplifies to 25x^8 16y^6. 
You square everything in this probelm to get rid of the parentheses. 
 
        
                    
             
        
        
        
Double angle (or half angle, depending how you look at it) identities:



So we have



Note that when taking the square root, we should take into account that that could yield two possible solutions, but we know  and
 and  , so it's also the case that
, so it's also the case that  .
.
Also, the reason we have equality in the last step can be explained like so:

(not unlike the process used to complete the square)