Question

How do i use cross multiplication to decide wheather a proportion is true or false?

3/4 = 15/16

Answer 1

3 * 16 =?? 4 * 15

Answer 2

4 * 15= 60
3 * 16= 48

now what i do? how do i know if its true or fasle?

Answer 3

Does 60 = 48??

Answer 4

Oh okay.. the number has to be the same in order for it to be true. So this problem would be false

Answer 5

Right. By cross-multiplying, you've proved this proportion to be false.