Square plus triangle equals 12; triangle times circle equals 24; circle times square equals 18 fast

Square plus triangle equals 12; triangle times circle equals 24; circle times square equals 18 fast

You can set the square as X, the triangle as y, and the circle as Z
So you can list them
X+Y=12
Y*Z=24
Z*X=18
Then the simultaneous equations are used to solve the unknowns
The square is 36 / 7, the triangle is 48 / 7, and the circle is 7 / 2