Answer:
K should not be equal to 1 or -1
Step-by-step explanation:
Check attachment for solution
Try, please, this:
1) Imagine, that pharmacist used 'x' gr. of 40% solution and 'y' of 70% solution.
Together (20 gr. of 52% sol.) it will be x+y=20.
2) From other side, the pharmacist combined 40x and 70y gramms, after obtaining together it is 52(x+y) gramms. In other words 40x+70y=52(x+y)
3)

Answer: 8 gr. of 70% solution and 12 gr. of 40%.
8.6 = -5
13.6 = 0
There should be another x value in your equation above, but with what you listen this is correct.
https://jhmsmath.weebly.com/uploads/2/7/7/5/27756807/8th_grade_countdown.pdf go to this link page 52-54
In this question , it is given that p represents cost of 1 container of popcorn . Therefore cost of 5 containers of popcorn = 5p and cost of 3 containers of popcorn = 3p .
And g represents cost of 1 container of granola bars. THerefore cost of 4 containers of granola bars = 4g and cost of 6 containers of granola bars = 6g .
According to the given question, the required linear equations are
5p+4g=42.50 , 3p+6g =34.50 .
And these are the the required system of linear equation .