Decimal: It’s easier to work with the numbers You can add, subtract, multiply and divide in your head (for the most part) instead of having to find common denominators and things like that.
Fraction: You can put repeating values in fraction form to represent them in a simpler way, as opposed to having to put the line over the repeating digits if it were in decimal form.
Power: Powers are just condensed forms of repeated multiplication, so they save space/time and you can use certain properties with some powers that allow you to multiply and divide them instantly.
Scientific notation: This is good when you’re dealing with numbers that have a lot of digits/place value. That can become confusing, so scientific notation is a way we can represent these numbers clearly and more condensed (takes less space/time).
        
                    
             
        
        
        
If Heather can do 2 in 10 minutes, then that means that she can do 12 in 1 hour. If Joel can do 3 in 15 minutes, then it means that he can do 12 in 1 hour. Add the number of problems they can do total and that will go between 30 and 50. It is just "less than", not "less than or equal to" because you want to know when the total number goes between the numbers. 
Therefore, the correct answer must be <span>30 < 24x + 5 < 50.</span>
        
             
        
        
        
Answer:
The second option
Step-by-step explanation:
The rate of change needs to stay constant.
The rate of change can be explained by looking at the "rise" (y) over the "run"(x)
The rate of change for the second option is 2.  We know this because...
Rise(2)
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Run(1)
Try looking at one of the points, now go up 2 and over 1, you should now be at the second point, do it again but twice, you should now be at the third point. A proportional relationship must also go through the origin (0,0)
 
        
             
        
        
        
Step-by-step explanation:
A²+B²=C²
 A²+4²=5²
A²+16=25
     -16 -16
A²=9 
√A=√9
   A=3