Answer:
Part 1) The best choice is Plan A
Part 2) The data is [tex]6\frac{2}{3}\ GB[/tex]
Step-by-step explanation:
Part 1)
Let
y ----> the cost per month
x ----> the number of GB of data per month
we know that
Plan A
[tex]y=5x+30[/tex]
Plan B
[tex]y=2x+50[/tex]
Find out which plan is the best choice if he uses five to eight GB of data per month
Plan A
For x=5 GB -----> y=5(5)+30=$55
For x=8 GB -----> y=5(8)+30=$70
so
with Plan A the cost is between $55 and $70 -----> average $62.5
Plan B
For x=5 GB -----> y=2(5)+50=$60
For x=8 GB -----> y=2(8)+50=$66
so
with Plan B the cost is between $60 and $66 ----> average $63
therefore
The best choice is Plan A
Part 2) How much data would Irfan need to use for both plans to cost the same?
we have
y=5x+30 ----> equation A
y=2x+50 ----> equation B
Solve the system of equations by elimination
Subtract equation B from equation A
0=5x-2x+30-50
0=3x-20
3x=20
[tex]x=\frac{20}{3}\ GB[/tex]
Convert to mixed number
[tex]x=6\frac{2}{3}\ GB[/tex] ----> for this data the cost is the same in both plans