Perform the following multiplication x plus 4 in parenthesis x plus 5 in parenthesis equals?

To perform the multiplication of (x + 4)(x + 5), you need to use the distributive property. This means you multiply each term in the first parenthesis by each term in the second parenthesis.

(x + 4)(x + 5) = xx + x5 + 4x + 45

Simplify this further to get x^2 + 5x + 4x + 20, which simplifies to x^2 + 9x + 20.