Answer:
The expression that shows how long the two machines will operate simultaneously is:
Step-by-step explanation:
We know that:
x: hours to manufacture a deck of cards for machine A
y: hours to manufacture a deck of cards for machine B
z: hours that machine A operates alone
The number of decks manufactured only by machine A is:
So, the remaining decks are given by:
Then, the combined rate of machines A and B would be:
The work-rate formula is:
Hence, the time that the two machines work simultaneously is: