In a certain code language, the symbols are redefined so that "+" means "minus", "x" means "divided by", "÷" means "plus" and "-" means "multiplied by". Using these rules, evaluate the expression 300 x 10 - 5 + 36 ÷ 57.

Introduction / Context:
This operator coding question reassigns meanings to the standard arithmetic symbols. You must decode each symbol carefully and then evaluate the resulting expression. These problems are designed to test whether you can switch between symbol meanings and still respect the normal precedence of operations.

Given Data / Assumptions:

• "+" means minus.
• "x" means divided by.
• "÷" means plus.
• "-" means multiplied by.
• Expression: 300 x 10 - 5 + 36 ÷ 57.
• After decoding, we apply usual arithmetic rules.

Concept / Approach:
The solution has two main steps. First, translate the coded expression into a standard arithmetic expression by replacing each symbol with its real meaning. Second, evaluate the translated expression using the familiar precedence, performing division and multiplication before addition and subtraction. Keeping the decoding step and the evaluation step separate helps prevent confusion.

Step-by-Step Solution:
Step 1: Start with 300 x 10 - 5 + 36 ÷ 57.Step 2: Replace "x" with "÷", "-" with "multiplied by", "+" with "minus" and "÷" with "plus".Step 3: The decoded expression becomes: 300 ÷ 10 * 5 - 36 + 57.Step 4: Evaluate division and multiplication first: 300 ÷ 10 = 30, and 30 * 5 = 150.Step 5: Substitute back: 150 - 36 + 57.Step 6: Now handle subtraction and addition from left to right: 150 - 36 = 114, and 114 + 57 = 171.

Verification / Alternative check:
We can quickly verify that no symbol was misinterpreted by re reading the definitions and ensuring that each occurrence in the original expression has been decoded. Re computing 300 ÷ 10 * 5 confirms the intermediate total 150. Adding and subtracting 36 and 57 again gives 171. Since the operations are straightforward, the chance of arithmetic error is low once decoding is correct.

Why Other Options Are Wrong:

• 150 would be the result if we stopped after multiplication and division.
• 230 and 234 imply incorrect ordering or mis decoding of plus and minus.
• 180 could arise from replacing one symbol incorrectly or ignoring part of the expression.

Common Pitfalls:
A major pitfall is inadvertently mixing the original symbol meanings with their coded definitions. Another common error is to calculate from left to right without prioritising multiplication and division after decoding. Always verify the decoded expression before doing any arithmetic to avoid compounding mistakes.

Final Answer:
After decoding and evaluating, the expression 300 x 10 - 5 + 36 ÷ 57 equals 171.