Multiply the difference between the numbers 3459 and 2451 by 2356 units. Subtract the product of the numbers 8 and 15 from the number 943. The floor length of the classroom is 12 m, the width is 2 times shorter. Find the perimeter of the classroom floor. Remember how to do the opposite. Formulate the problem in reverse and solve it.

Here are the results with concise steps. 1) (3459 − 2451) × 2356 - 3459 − 2451 = 1008 - 1008 × 2356 = 2,374,848 - Product: 2,374,848 (in square units, if the difference is in units) 2) 943 − (8 × 15) - 8 × 15 = 120 - 943 − 120 = 823 - Result: 823 3) Perimeter of the classroom floor - Given length = 12 m, width is 2 times shorter → width = 12 / 2 = 6 m - Perimeter P = 2 × (length + width) = 2 × (12 + 6) = 36 m - Reverse check: If P = 36 m and L = 12 m, then W must satisfy 2 × (12 + W) = 36 → W = 6 m, which is consistent. Final answers: - Product: 2,374,848 - Subtraction result: 823 - Perimeter: 36 m