In the following question, by using which mathematical operators will the expression become correct? 15 _ 3 _ 4 _ 20

Introduction / Context:
This is a simple operator-insertion puzzle. We are given numbers in a fixed order and must choose a sequence of operators from the options so that the resulting mathematical statement is numerically correct. Such questions test understanding of the basic arithmetic operations and, very importantly, the rule of operator precedence: multiplication and division are done before comparison or equality checks.

Given Data / Assumptions:
- Expression skeleton: 15 _ 3 _ 4 _ 20
- The three blanks must be filled in order with the three operators given in one option.
- Normal arithmetic precedence is assumed: division and multiplication first, then comparison or equality.
- We must find the option that makes a true statement.

Concept / Approach:
The strategy is to test each option as a complete expression. For every option, substitute the operators into the blanks, simplify the left-hand side following arithmetic rules, and then check whether the relation with 20 is true. Because there are only four options, this trial-and-check method is quick and reliable.

Step-by-Step Solution:
Step 1: Test option (a): 15 × 3 ÷ 4 > 20. Compute: 15 × 3 = 45; 45 ÷ 4 = 11.25. The statement is “11.25 greater than 20”, which is false. Step 2: Test option (b): 15 ÷ 3 × 4 < 20. Compute: 15 ÷ 3 = 5; 5 × 4 = 20. The statement becomes “20 less than 20”, which is false. Step 3: Test option (c): 15 ÷ 3 × 4 = 20. Compute: 15 ÷ 3 = 5; 5 × 4 = 20. Now the statement is “20 equals 20”, which is true. Step 4: Test option (d): 15 + 3 × 4 = 20. Compute: 3 × 4 = 12 first; then 15 + 12 = 27. The statement becomes “27 equals 20”, which is false. Step 5: Since only option (c) produces a true equation, it must be the correct choice.

Verification / Alternative check:
We can verify option (c) directly: 15 ÷ 3 × 4 = 5 × 4 = 20; right side is 20, so both sides match exactly. The equality sign is therefore justified. No other option yields a valid comparison with 20.

Why Other Options Are Wrong:
- Option (a) gives 11.25 on the left side, which is not greater than 20, so the inequality fails.
- Option (b) gives 20 on the left side, which is not less than 20, so the relation is false.
- Option (d) produces 27 on the left side, which is not equal to 20, so the equation is incorrect.

Common Pitfalls:
A frequent mistake is to ignore operator precedence and, for example, compute “15 ÷ 3 × 4” from left to right but then incorrectly add before multiplying in option (d). Another pitfall is to judge correctness by rough estimation instead of performing exact calculations. Always apply the standard rule: perform multiplication and division before addition or subtraction, and only then evaluate the equality or inequality.

Final Answer:
The expression becomes correct with the operators “÷, x and =”, giving the true equation 15 ÷ 3 × 4 = 20.