Ihate algebra and my teacher doesn't teach us this

Okay.  Start easy.  If you look at the page, there's a spot where it says tall sandshoe - tall boot = tall sandshoe. Ths automatically means that tall boot must be 0. So put 0 down the bottom against tall boot, and put it in against any other tall boots in the picture, as well.

Gym boot (gym boot x gym boot = slipper) has to be 2, because further down, it says gym boot + gym boot = slipper as well.

That also means slipper must be 4.

Riding boot = riding boot x short sandshoe, tells me that short sandshoe must be 1.  If you put these values in all the places, as you work them out, it makes it easier to work out the next one.
See high heeled shoe at the top? three of those has to add up to less than 11.  We already have values for 1 and 2, so we can guess that high heeled shoe = 3. If that's the case, then slip-on must be 9.
Lower right, we have  slip-on - high heeled shoe = short boot. 9 - 3 = 6.  So short boot is 6.

For the last three, I just put them in, and tried the boots, until I got it right.

My answers, from left to right along the row of shoes:

9 4 1 6 0 8 5 3 2 7.