By setting up each equation as a proportion and cross multiplying, we determined the values of x to be x = 2 for the first problem, x = 1 for the second problem, and x = 36 for the third problem.
To solve the first proportion problem, we set up the equation x/3 = 12/18. By cross multiplying, we get 18x = 3 × 12, which simplifies to 18x = 36. Dividing both sides by 18, we find x = 2.
For the second proportion problem, we have x/2 = 4/8. Cross multiplying here gives us 8x = 2 × 4, so 8x = 8. Dividing by 8, we find x = 1.
In the third proportion problem, the setup is 2/6 = 12/x. Cross multiplying gives us 2x = 6 × 12, so 2x = 72. Dividing by 2, we then get x = 36.