Jen take x hours.
Carl (x-3)hours.
Jen+carl take two hours;
This means;
In 1 hour, for they work
=
=
Working together, they take two hours;
Take reciprocal of above equation and equate to two;
=
-3x=4x-6
-x-6x+6=0
x(x-1)-6(x-1)=0
(x-6)(x-1)=0
Take the bracket x-6=0 so that Carl works positive hours
x-6=0
x=6
Carl (x-3)hours.
Jen+carl take two hours;
This means;
In 1 hour, for they work
=
=
Working together, they take two hours;
Take reciprocal of above equation and equate to two;
=
x(x-1)-6(x-1)=0
(x-6)(x-1)=0
Take the bracket x-6=0 so that Carl works positive hours
x-6=0
x=6