Whenever you cross multiply, which side do you start with first? Do i start on the left or right?

Answer 1

Left or right does not really matter. What is important is where the unknown is located.

A rule of thumb is to multiply together the two numbers beside the unknown, and divide by the one across.

If a,b,c are known, and D is not known, and the equation looks like:
a c
-=-
b D
then you could write

D=c×b÷a

or for
a b
-=-
D c
then
D=a×c÷b

Answer 2

thankyou!

Answer 3

You're welcome!

Answer 4

The angryro