and1ms238 wrote:I was reviewing the BTG Flash cards and I came across this flash card. Can someone help explain to me the concept of 'inverting' here?

In the example, is A the amount of time?

For example: If machine A makes 5 gallons per Hour and machine B makes 8 gallons per hour, then how many can the two machines make together in 1 hour?

How does the formula in the flash card relate? Thank you much in advance.

see if a man do work in A hrs and other in B hrs say
so how much work he will do in 1 hr
a's work in 1 hr = 1/A
similarly B's work in 1 hr. = 1/B
total work in 1 hr = 1/A + 1/B

also if both can do work in T hr..
so their combined 1 hr work = 1/T

hence 1/A + 1/B =1/T/..
Hope it solves ur confusion....

and1ms238 wrote:I was reviewing the BTG Flash cards and I came across this flash card. Can someone help explain to me the concept of 'inverting' here?

In the example, is A the amount of time?

For example: If machine A makes 5 gallons per Hour and machine B makes 8 gallons per hour, then how many can the two machines make together in 1 hour?

How does the formula in the flash card relate? Thank you much in advance.

A is indeed the amount of time taken

In the example given , A makes 5 gallons per hour and B makes 8 gallons per hour; A&B together will make 13 gallons per hour.

If the question were A takes 2.6 Hours to make 13 gallons and B takes 1.625 Hours to make 13 gallons how much time will it take for A&B working together to make 13 gallons

In such scenario => 1/2.6+1/1.625 = 1/T

=> 1/1 = 1/T

T = 1 hour

I hope the concept is clear; A , B and T refer to time to get the specific amount of work done, not work done per time.