Linear equations

Question

It’s time to get a new cell phone plane - which will you choose? Using linear equations, you can answer some questions about which plan is best based on the number of text you plan to send. Y =( cost per text)(number of texts) +( base cost).

Plan 1 - The basic plan is $32.00 per month plus $0.25 per test message.

Plan 2 - The basic plan is $45.00 per mouth plus $0.10 per text message.

Answer 1

t = number of text messages

 

Plan 1:

 

y₁(t) = 0.25t + 32.00

 

Plan 2:

 

y₂(t) = 0.10t + 45.00

 

Find the range of t where y₁(t) < y₂(t) by solving an inequality in t.

 

0.25t + 32 < 0.1t + 45

 

(0.25 - 0.1)t < 45 - 32

 

t < 13/0.15 ≅ 86.7

 

Then plan 1 is better if you plan to send 86 or fewer texts, while plan 2 is better if you plan to send 87 or more texts.