homework and exercises - Image formation (lenses)

I have a question regarding image formation by lenses. It is the following:

A lense with a focal length of $-48.0cm$ forms an image $17.0cm$ to the right of the lense. Where is the object positioned?

My attempt at a solution:

Well, since the focal length is negative, we know that the lense is divergent (concave). The problem statement says that the image is to the right of the lense, so $s_i=17cm (>0)$

We can compute the position of the object by using the formula below:

$$\dfrac{1}{d_0}+\dfrac{1}{d_i}=\dfrac{1}{f}$$

Changing what we know for the values, we get:

$$\dfrac{1}{d_0}+\dfrac{1}{17}=- \dfrac{1}{48}$$

And doing the calculations, it comes down to:

$$s_0=-12.55$$

However, the solutions say the solution is $s_0=26.3$. One can get that if we take $s_i$ to be negative, which is wrong, in my opinion. (?)

So, why am I wrong? Or am I correct?