Answer:
12 students didnt turn in a extra credit project at the end of the semester.
Step-by-step explanation:
Both 3x and 9 are a multiple of 3, so we can factor out a 3:
3x + 9 = 3 (x + 3)
The answer will be 10 because you plug in y=-×+12 in the equation 4x-2y=36. After you solve and do distributive property your new equation should be 4x+2x-24=36, then you add the like terms of 4x and 2x which will equal to 6x and your new equation should be 6x-24=36. Add 24 from both sides and your equation should be 6x=60, then you divide 60 by 6 and your final answer will be x=10 or 10
Let x represent the amount of 10% solution used.
Let y represent the amount of 25% solution used.
Since 30 liters of 15% solution are being made, our first equation is
x + y = 30
Now we deal with the actual peroxide in each solution.
x liters of 10% peroxide contain 0.1x liters of peroxide.
y liters of 25% peroxide contain 0.25y liters of peroxide.
30 liters of 15% peroxide contain 0.15 * 30 = 4.5 liters of peroxide.
From this information, we can write our second equation.
0.1x + 0.25y = 4.5
We have a system of equations:
x + y = 30
0.1x + 0.25y = 4.5
Multiply the first equation by -0.25 and add to the second equation.
-0.25x - 0.25y = -7.5
0.1x + 0.25y = 4.5
---------------------------
-0.15x = -3
x = 20
Answer: 20 liters
