I got k ≥ -7. Hope this helps!
Part C:
y = total cost
M = minutes
You can talk on the phone only 100 minutes per month
Company A:
y = 0.04M + 5
y = 0.04(100) + 5
y = 4 + 5
y = 9 $9 per month
Company B:
y = 0.10M + 2
y = 0.10(100) + 2
y = 10 + 2
y = 12 $12 per month
Company A offers the best deal because at Company A you have to pay $9 for 100 minutes per month, and at Company B you have to pay $12 for 100 minutes per month, so you have to pay $3 less.
Part D:
1.) With a budget of $30, Company A would allow me to talk longer on the phone. I know this because for Company A, you pay $3 less per month for the same amount of minutes as Company B. This means that I will save more money with Company A, and I can buy more minutes. (something like this)
1/10 as a decimal would be 0.1. Now just add the 8 to it and it would be 8.1.
I'm Pretty Sure The Answer Is x=2
Hope This Help's
A=3B
4.35A+5.40B=780.95
Substitute 3B into A for the second equation:
4.35(3B)+5.40B=780.90
13.05B+5.40B=780.90
18.45B=780.90
B=42.33
Plug into equation 1:
A=3B
A=3(42.33)
A=126.98
