In order to calculate the work done, you need to know how far she lifted it. We don't know the distance, so it's not possible to calculate the work.
All we have right now is a laundry basket that weighs 75N being lifted with 100N of force. Reading carefully, we know that the vertical forces on the laundry basket are unbalanced, and the NET force on it is 25N upward.
We can go further if we assume that all of this is happening on Earth. Then, since the basket's weight is 75N, its mass is (W/g) = 7.653 kg. From Newton #2, we know that F=mA, which we can re-arrange to state that A = F/m. So in the case of the unfortunate laundry basket,
A = F/m = (25N / 7.653 kg) = <em>3.27 m/s²</em> .
The laundry basket is accelerating to the sky as we speak, at the rate of 3.27 meters per second². As it cleared the fence a few moments ago, Mrs. O'Leary's cows next door spotted it, panicked, ran into the barn and clear through the back wall into the pasture. Now, a full minute after lift-off, the laundry basket has achieved a vertical velocity 196 m/s, and is 5.88 kilometers downrange. After a simple roll maneuver, it may be in orbit soon, if the 100N force on it continues.
