Chapter 4.5, Problem 4ES

For each step, write the letter that gives an explanation of what was done on that step.

a. Combining like terms

b. Multiplying monomials

c. Using the commutative law for multiplication

d. Using the distributive law

$\begin{array}{l}\left(2x+3\right)\left(5x-4\right)\\ =\left(2x+3\right)\left(5x\right)-\left(2x+3\right)\left(4\right)\\ =\left(5x\right)\left(2x+3\right)-4\left(2x+3\right)\\ =\left(5x\right)\left(2x\right)+\left(5x\right)\left(3\right)-4\left(2x\right)-4\left(3\right)\\ =10x^2+15x-8x-12\\ =10x^2+7x-12\end{array}$

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