Graphic algebra problems. Very hard

Select your preferred difficulty level for algebra exercises. Very hard. Free and interactive.

21 - 1 - flip flops.png = bucket.png + 1
shell 2.png + 2 = 22 - 2 - bucket.png
shell 2.png + 3 = 19 + 1 - flip flops.png
Can you calculate the value of each of the elements?
flip flops.png =
bucket.png =
shell 2.png =