logical deduction - What is the solution of the last operation?

Each symbol represents a number between 0 and 9. You need found the number which is the solution to the last operation. The two triangles in the first operation and the triangle and the rectangle of the third operation represent a number of two digits, not a multiplication operation.

So, which is the number that corresponds to the last operation?

Answer

Let G, R, Y, B denote the digits corresponding to the four shapes in the order they appear (green star, red octagon, yellow triangle, blue rectangle).

In the first equation,

two 1-digit numbers sum to YY, so Y=1 (22 is too large).

In the second equation we learn B=R+1.

Now the third equation is

1B-R = 1(R+1)-R = 11,

so the answer is

11, or two yellow triangles.