Question

After interchanging + & x and 15 & 30, which of the following equations will hold true?

• A. (15+2)×30=60
• B. (30+3)×15=40
• C. (15+4)×30=135
• D. (30+1)x15=40

Answer 1

Answer:

C. (15+4)×30=135

We interchange:

• + ↔ ×

• 15 ↔ 30

Now test each option after swapping.

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1. (15 + 2) × 30 = 60

After swap:

• 15 → 30, 30 → 15

• becomes ×, × becomes +

So:
$(30 × 2) + 15 = 60 + 15 = 75 \neq 60$

False

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2. (30 + 3) × 15 = 40

After swap:
$(15 × 3) + 30 = 45 + 30 = 75 \neq 40$

False

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3. (15 + 4) × 30 = 135

After swap:
(30 × 4) + 15 = 120 + 15 = 135
True

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4. (30 + 1) × 15 = 40

After swap:
$(15 × 1) + 30 = 15 + 30 = 45 \neq 40$

False

Final Answer:

(15 + 4) × 30 = 135