You haven't mentioned the + and - signs for the values Brother.

Let the two lenses of focal length be taken as f1 and f2.

Given,

f1 = +10cm , f2 = -5cm.

We should find the net value of power, so use the power of the lens formula.

Power of lens is defined as the reciprocal of its focal length and represent by the letter P.

P = 1/f1

P = 1/+10

P = +0.1D.

"D" refers to the "Dioptre".

This means the lens prescribed is Convex lens as the sign is +ve.

P = 1/f2

P = 1/-5

P = -0.2 D.

This means the lens prescribed is Concave lens as the sign is -ve.

**Given Information:**

- Focal length of first lens, f1 = 10 cm
- Focal length of second lens, f2 = 5 cm

**Net Power:**

The net power of the combination of lenses is the sum of the individual powers of the lenses.

**Power of a Lens:**

The power of a lens is given by the formula:

P = 1/f

Where P is the power of the lens and f is the focal length of the lens.

**Calculating the Power of the First Lens:**

Given that the focal length of the first lens is 10 cm, we can calculate its power using the formula:

P1 = 1/f1
= 1/10
= 0.1 diopters

**Calculating the Power of the Second Lens:**

Given that the focal length of the second lens is 5 cm, we can calculate its power using the formula:

P2 = 1/f2
= 1/5
= 0.2 diopters

**Calculating the Net Power:**

To find the net power of the combination of lenses, we need to add the individual powers of the lenses.

Net Power = P1 + P2
= 0.1 + 0.2
= 0.3 diopters

Therefore, the net power of the combination of lenses is 0.3 diopters.