Question

Evaluate the expression. $$ 25-\left[\frac{3}{10}(6 \cdot 5)-2\right] $$

Short answer

The final evaluated result of the given expression is 18.

Step-by-step solution

Solve Expression Inside the Brackets

Solve the multiplication operation first within the brackets by multiplying 3/10 and 6*5. i.e., \( \frac{3}{10} \cdot 30 = 9 \)

Continue Solving Expression Inside the Brackets

After getting the result of the multiplication expression, subtract 2 from the result. i.e., \( 9 - 2 = 7 \)

Perform the Final Subtraction

Subtract the result obtained from step 2 from 25. i.e., \( 25 - 7 = 18 \)

Key concepts

Order of Operations

The order of operations is a fundamental concept to correctly evaluate expressions in algebra. It's like a set of traffic signals that guides us on which path to follow when faced with multiple operations. This set of rules is known by the acronym PEMDAS, which stands for Parentheses, Exponents, Multiplication and Division (from left to right), and Addition and Subtraction (from left to right).

Using PEMDAS in our exercise,
$$ 25-\left[\frac{3}{10}(6 \cdot 5)-2\right] $$
we first handle the operation inside the brackets because it is the innermost parentheses. Inside, we follow PEMDAS which leads us to multiply before subtracting, and finally, we perform the subtraction outside the brackets. Understanding and applying the order of operations is essential to simplify expressions accurately and is the first step in any algebraic solution.

Arithmetic Operations in Algebra

Arithmetic operations in algebra are the building blocks for simplifying expressions and solving equations. These operations include addition, subtraction, multiplication, division, and sometimes exponentiation. Algebra extends basic arithmetic by incorporating variables (like x or y) into expressions, but the fundamental operations remain the same.

In the context of our exercise, we start with mulitiplication:
$$ \frac{3}{10} \cdot (6 \cdot 5) $$
Here, we eventually perform a multiplication between a fraction and an integer. Recognizing how to handle such operations is crucial. Remember, in algebra, multiplication between a number and a variable, or between two variables, is often implied with juxtaposition (e.g. 3x or xy), and it follows the same arithmetic principles.

Simplifying Algebraic Expressions

Simplifying algebraic expressions involves reducing them to their simplest form, making calculations and understanding easier. This process often includes combining like terms, distributing, and following the order of operations. Simplification may also involve factoring expressions and canceling common factors.

In our example, after handling the multiplication inside the brackets, we simplify the expression by subtracting:
$$ 9 - 2 = 7 $$
This reduction is key to making the expression as straightforward as possible, leading to the final subtraction from the whole number 25. Different expressions require different simplification techniques, but the goal remains the same: to arrive at the simplest form for easy interpretation.