Hello, Joe0430!
Pascal is absolutely correct . . . let me baby-talk through it.
John can paint a room in 8 hours.
Mary can paint the same room in 6 hours.
How long will it take them if they paint the room together.
Let x = number of hours if John and Mary work together.
John can paint the room in 8 hours.
. . In one hour, he can paint 1/8 of the room.
. . In x hours, he can paint x/8 of the room.
Mary can paint the room in 6 hours.
. . In one hour, she can paint 1/6 of the room.
. . In x hours, she can paint x/6 of the room.
Together, in x hours, they can paint:
.x/8 + x/6
.of the room.
. . But this adds up to one (1) room, right?
And
there is our equation:
. x/8 + x/6 . = . 1