Explanation:
well, 5×4 IS 20.
I am not sure, what your teacher wants here.
and therefore, as a fact, 9×2 = 18.
maybe it is to show the fraction relationship between the teens of the first operation and the terms of the second.
9 = 5×9/5
2 = 4×2/4
so, 9×2 = 9/5 × 2/4 × 20 = 18/20 × 20 = 18
I consider this nonsense, but it is the only thing I can currently think of to do with these operations in relation to each other.