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
The answer is b
Because you have to add da x and dat is 2x den add da numbers which is 4
X=4
Y=-0.5
Do you need an explanation?
Use elimination
Multiply first equation by 4
12a - 8b = 56
12a + 9b = 39
Subtract both
-17b = 17
b = -1
Plug in -1 for b
3a - 2(-1) = 14
3a = 12, a = 4
Final answer: a = 4, b = -1
18 min per pound
324 min. = X
______ _____
18 1 pound
324 x 1 = 324 324/18= 18 pounds
Cross multiply then divide as above.
