Answer:
- The system of equations is x + y = 85 and 7/20x+2/5y=31
- To eliminate the x-variable from the equations, you can multiply the equation with the fractions by 20 and multiply the other equation by -7.
- B-She used 60 minutes for calling and 25 minutes for data.
Step-by-step explanation:
It is always a good idea to start by defining variables in such a problem. Here, we can let x represent the number of calling minutes, and y represent the number of data minutes. The the total number of minutes used is ...
x + y = 85
The total of charges is the sum of the products of charge per minute and minutes used:
7/20x + 2/5y = 31.00
We can eliminate the x-variable in these equations by multiplying the first by -7 and the second by 20, then adding the result.
-7(x +y) +20(7/20x +2/5y) = -7(85) +20(31)
-7x -7y +7x +8y = -595 +620 . . . . eliminate parentheses
y = 25 . . . . . . . . simplify
Then the value of x is
x = 85 -y = 85 -25
x = 60
We know that
if <span>(ax + b)(cx - d) = 0
then
</span><span>(ax + b)= 0-----> ax=-b------> x=-b/a
and
</span><span>(cx - d) = 0-----> cx=d------> x=d/c
therefore
the answer is the option
</span><span>C. -\frac{b}{a}</span>
(f o h) = -(x - 3/3) - 1
(f o h) = (-x + 3)/3 - 1
(f o h)(1) = (-1 + 3)/3 - 1
(f o h)(1) = 2/3 - 1
(f o h)(1) = -1/3
Answer:
your answer might be 3
Step-by-step explanation:
