Question

Gerardo’s texting plan cost $20 per month, +0.05 per text message that is sent or received. Amelia’s plan cost $10 per month and $0.25 per text. Using the graph below, which statement is true?

Answer 1

Explanation:

Let's turn that into a linear system:

\{ {{y=0.05x+20} \atop {y=0.25x+10}} .{y=0.25x+10y=0.05x+20.

Set the equations equal to each other and solve:

0.05x+20=0.25x+100.05x+20=0.25x+10

0.2x=100.2x=10

x=50x=50

We then plug in to get yy :

0.25(50)+10=22.50.25(50)+10=22.5

The solution to the system is \{ {{x=50} \atop {y=22.5}} .{y=22.5x=50. .

Now, let's turn our attention to the statements.

The first one is false: Emilia's rate is higher, and the two plans cost the same at 50 texts, after which point Hiroto's plan becomes cheaper!

The second one is also false: we already figured out that the lines intersect at x=50x=50 .

The third statement is also false: as above, the lines intersect at x=50x=50 .

The fourth statement is true: the lines intersect at x=50x=50 .

In conclusion, the fourth statement - "Both plans cost the same when 50 texts are sent" - is true.

Cred to ultroid