Question

Simplify the expression.

$\left(21x+15y\right)-\left(9x-4y\right)$

Short answer

The final expression is $12x+19y$.

Step-by-step solution

Step 1. Define an expression.

A mathematical expression is a combinations of numbers and variables ordered with mathematical operations.

Step 2. Define like and unlike terms.

In algebra, like terms are the terms that have the same variables and powers.

The unlike terms are two or more terms that are not like terms.

Step 3. Simplify the expression 21x+15y−9x−4y.

Simplify the expression $\left(21x+15y\right)-\left(9x-4y\right)$by combining the like terms.

role="math" localid="1647956395837" $$\begin{gathered} \left(21x+15y\right)-\left(9x-4y\right)=21x+15y-9x+4y \\ =21x-9x+15y+4y \\ =12x+19y \end{gathered}$$

Therefore the final expression is $12x+19y$.