Hi Tanisha,

Your question makes perfectly good sense. To avoid this type of confusion mathematicians have developed conventions in the writing of mathematical expressions. One of these conventions or rules is that powers are performed before multiplication. For example the expression $7 \times 3^2$ is evaluated by

\[7 \times 3^2 = 7 \times 9 = 63.\]

If you want to square both the 7 and the 3 you would need to write $(7 \times 3)^2$ since one of the conventions concerning order of operations is that you perform whatever is inside parentheses or brackets first. Thus

\[(7 \times 3 )^2 = (21)^2 = 441.\]

In your expressions $5x^2$ and $4x^3$ there is an implied multiplication between the $5$ and the $x^2$ and also between the $4$ and the $x^3$ and hence

\[5x^2 \times 4x^3 = 5 \times x^2 \times 4 \times x^3\]

and since multiplication is commutative

\[5x^2 \times 4x^3 = 5 \times x^2 \times 4 \times x^3 = 5 \times 4 \times x^2 \times x^3 = 20 \times x^5 = 20x^5\]

I hope this helps,
Penny