Answer:
To write 252 cards together Courtney and Victoria will take = 140 minutes or 2 hours and 20 minutes.
Step-by-step explanation:
Given:
Courtney writes 4 cards in 10 minutes
Victoria writes 14 cards in 10 minutes.
To find the time taken by them to write 252 cards working together.
Solution:
Using unitary method to determine their 1 minute work.
In 10 minutes Courtney writes = 4 cards
So,in 1 minute Courtney will write =
cards
In 10 minutes Victoria writes = 14 cards
So,in 1 minute Victoria will write =
cards
Now, Courtney and Victoria are working together.
So, in 1 minute, number of cards they can write together will be given as:
⇒

Since we have common denominators, so we can simply add the numerators.
⇒

Again using unitary method to determine the time taken by them working together to write 252 cards.
They can write
cards in 1 minute.
To write 1 card they will take =
minutes
So, for 252 cards the will take =
minutes
140 minutes = (60+60+20) minutes = 2 hours and 20 minutes [ As 60 minutes = 1 hour]
So, to write 252 cards together Courtney and Victoria will take = 140 minutes or 2 hours and 20 minutes.