Solve the variables game

This is a pre algebra game where the grade 4 child is expected to know how to find the unknown variable in the equation. It is a quiz that comes with multiple choices. Once the player have calculated the equation and found the unknown value, he or she has to pick the correct answer. The correct answer will fill the jar, if the answer is not correct, the level of the liquid will not go up. The game is good for testing how well the child understands how to solve the algebra equations.