I’m losing

you are trying to decide which cell phone plan to purchase. plan a chargeres $40 for a new phone and $20 a month for usage. plan b provides the phone for free, but has a fee of $30 a month for usage.
use the substitution method to determine when the two plans will cost the same.

In 4 months the two plans will cost the same.

Step-by-step explanation:

Let represent the number of months of usage of phone

Let represent the total amount charged by the plans.

Plan A:

Plan A charges $40 for a new phone and $20 for per month usage.

Fixed charge = $40

Per month usage charge = $20

Usage charges in dollars for months will be =

Thus total charges in dollars can be given as:

A)

Plan B.

Plan B provides the phone for free, but has a fee of $30 for per month usage.

Fixed charge = $0

Per month usage charge = $30

Usage charges in dollars for months will be =

Thus total charges in dollars can be given as:

B)

In order to determine the number of month in which the two plans will charge same we will equate the equations.

Substituting equation B in equation A.

Solving for

Subtracting both sides by

Dividing both sides by 10.

∴

Thus, in 4 months the plans will cost the same.

the total estimated nappy use.=10,500,000

step-by-step explanation:

given that on an average the average baby uses 3528 napkins.

in a particular year 2014, the number of births were 299697 in new south wales.

rounding off the number of births to the nearest hundred thousand we have

no of birtsh = 300000

also rounding off the average usage to nearst thousand we get

average use of a baby = 3500

hence total number of nappy estimated to be used = 3500x300000

= 10,500,000

answer is 10,500,000 nappies