The first (and most typical) way to find distance of two points is by using the distance formula.

One alternative is the Manhattan metric, also called the taxicab metric. This option is much more complicated, and rarely used in high school math. d(x,y)=∑i|xi-yi|
To find the cross product, you can set this up as a proportion. Please see the attached paper for one of the proportions you could use.
You would then multiply the numbers that are diagonal from each other.
You would have 21(8) = 12x or
168=12x.
Answer:
4 11/12
Step-by-step explanation: