25282

We turned it into algebra this is the lettering. square- q
circle-p
triangle-r
hexagon-s
then we did this

3p+q=20
3p+r=18
2p+q+r=22

so p-r=-2
3p+r=18

Then we added p with 3p that was 4p then -r with r that was 0 then 18 - 2 thats 16
so therefore 4p = 16 hence p=4 (circle = 4)
putting this into our second equation gives r=6 ( triangle =6)
if we substitute back into the grid we get s=7(hexagon)and q = 8 ( square)

this gives the final solution: ? = 21

:) :)