**Combination of Lenses**

To find the power of a combination of lenses, we need to consider the concept of lens power. The power of a lens is given by the formula:

Power (P) = 1/f

Where f represents the focal length of the lens.

**Given Information**

In this case, we have two lenses with focal lengths of -25 and 50. The negative sign indicates that the lenses are concave.

**Finding the Power of Individual Lenses**

To find the power of each lens, we can use the formula mentioned earlier:

Power (P1) = 1/f1 = 1/-25 = -0.04
Power (P2) = 1/f2 = 1/50 = 0.02

Here, P1 represents the power of the first lens and P2 represents the power of the second lens.

**Finding the Power of the Combination**

When two lenses are joined together, their powers can be added to find the power of the combination.

Power (P) = P1 + P2

Substituting the values we found earlier:

P = -0.04 + 0.02 = -0.02

The power of the combination is -0.02.

**Interpretation**

The negative sign in the power value indicates that the combination of lenses is diverging. This means that when parallel rays of light pass through the combination of lenses, they will diverge away from each other.

**Conclusion**

The power of the combination of lenses with focal lengths -25 and 50 is found to be -0.02. This negative power indicates that the combination is diverging.