Answer:
(1, –5)
Step-by-step explanation:
It is relatively easy to try the offered solutions to see what works.
<u>(1, -5)</u>
3(1) +10(-5) = -47 . . . true
5(1) -7(-5) = 40 . . . true
(1, -5) is the solution
_____
As a check, you can try some of the other choices:
<u>(1, 5)</u>
3(1) +10(5) ≠ -47
<u>(-1, -5)</u>
3(-1) +10(-5) ≠ -47
<u>(-1, 5)</u>
3(-1) +10(5) ≠ -47
None of the other choices works in the first equation, so they're not the solution.
130÷5=26 20÷5=4+26=30 each payed 30 dollars for the buffet
5x - 20 = 8x - 65
-20 = 3x - 65
3x = 45
x = 15
12,571.4286 you subtract 1000 from the total, and divide by 7.
Answer:
The volume of the solution with 20% acid is 27 gallons and the one with 10% acid is 18 gallons
Step-by-step explanation:
Myra needs to mix "x" gallons of the solution with 20% and "y" gallons of the solution with 10%. The volume of the final solution must be 45 gallons, therefore:
x + y = 45
The concentration of acid of the final solution is:
0.2*x + 0.1*y = 45*0.16
0.2*x + 0.1*y = 7.2
Therefore we have a system of equation:
x + y = 45
0.2*x + 0.1*y = 7.2
We need to multiply the first equation by -0.1:
-0.1*x -0.1*y = -4.5
0.2*x + 0.1*y = 7.2
We now sum both equation:
0.1*x = 2.7
x = 2.7/0.1 = 27 gallons
y = 45 - 27 = 18 gallons
