We can actually solve for the individual variables in this question to subsequently find the product 12xyz:
x = 10
y = 20/3
z = 5
12xyz = 12*10*20/3*5 = 4*10*20*5 = 4000
As you can see, solving for the individual variables and then finding the product takes several more steps than the approach Chris used. Also, the math is a little more complicated. However, both are valid ways to get to the correct solution :)
2 Explanations