Step-by-step explanation:

Answer:
A.
Step-by-step explanation:
x - 9 = 0
+ 9 + 9
---------------
x = 9
Answer:
x = 60
Step-by-step explanation:
t = 
15 = k/68
k=1020
~~~~~~~~~~~
17 = 1020/x
x = 1020/17
x = 60
Answer:
one thousand two hundred thirty four & 56/100
For this problem you can create a proportion.
Since 31,100 copies is 7.8% of the total copies spoke up to date you can make this proportion:
31,100. 7.8%
——— =. ———
x. 100%
Now you cross multiply and you will get
7.8x=3,110,000
After this you solve for x by isolating the variable.
7.8x/7.8. 3,110,000/7.8
x=398,717.949
Since the question asks you to round to the nearest whole number which is 7 then the final answer would be 398,718
Answer: There has been 398,718 copies sold to date.