Hello.
First of all, let the number be t.
8 times t can be written like this:

Notice that the number is before the variable and the times sign (×) is not there.
We can write it as 8×t, but we usually write it as 8t.
The sum of means we add:
8t+21
Now, "less than" is "<" :

Therefore, the answer is

I hope it helps.
Have a nice day.

 
        
             
        
        
        
Well, given that a quarter equals 5 nickels, we can reason that, in order to get 12 coins, we would have to get 10 nickels (equals 50 cents) and 2 quarters (the other 50 cents, to make a dollar).
You didn't say whether you needed this expressed in a mathematical formula, but knowing the answer already, it shouldn't be hard to come up with one if necessary.
Hope this helps.
        
                    
             
        
        
        
<span>Table:
Class Boundaries         Frequency
5-10                              8
10-15                            9
15-20                          15
20-25                          10
25-30                           8
30-35                           6
                                ----------
total                           56
Average =
[5+10]/2*8+[10+15]/2*9+[15+20]/2*15+[20+25]/2*10+[25+30]/2*8+[30+35]/2*6
---------------------------------------------------------------------------------------------------
</span>                                                      56
That is 1075 / 56 = 19.2
Answer: 19
        
             
        
        
        
Answer:
 21 1/3 inches
Step-by-step explanation:
Inverse variation means that when the frequency goes up by a factor of 576/256 = 9/4, the length of the string goes down by a factor that is the inverse of that, 4/9.
 4/9·48 inches = 21 1/3 inches