Couple of things wrong here, the two soldiers are misleading. Do they mean times? Do they mean the two numbers are next to each other? Or is it implying one is a power.
First assume the soldier in first equation to be x. The first following soldier ( the one with the small knife) will be substituted by y and the last by z ( the one with the torch).
Either 9 if you assume the 2 identical soldiers next to eachother in the last equation to be added up eachother which gives 10. You can derive this from the 1st equation by dividing 15 by 3 which results into 5. ( i.e. 3x = 15 => x= 5) For the 2nd and 3rd equation you need to substitute the first soldier in the 2nd equation by y = 12 - (x + z) into the 3rd equation which results into 12 - (x+z) + z+z = 10. After simplifying this equation and using the previously calculated x=5, you'll get that z = 3. So as mentioned earlier if we rewrite the last equation assuming we add up the x's we'll get 2x +z -y = 2 *5 +3 -4 =9
If we assume the identical soldiers in the lasy equation to be multiplied by eachother will be
x^2 + z -y = 25 + 3 -4 =24
And last but not least if we assume the identical soldiers in the last equation to be considered as digits that create a number when putting them next to eachother we'll get
xx +z -y = 55 + 3 -4 = 54
N.B.: I purposefully noted the operations for multiplications so when not used you wouldn't assume it would be multiplication.
I think this is a fine example of having two fora (this one and Discord) is not the smartest thing to do. The same contest was also on Discord. There winners were already announced I think a week after the start of the contest.
Here (on the dead forum) the contest still lingers on forever and no winner will be announced here. It is difficult to get used to a dead forum.