Final answer:
To subtract numbers written in scientific notation, convert them to the same power of 10. Then subtract the decimal parts and keep the power of 10 unchanged. Finally, write the answer in standard form.
Step-by-step explanation:
To subtract numbers written in scientific notation, you need to ensure that the powers of 10 are the same. In this case, convert 4 × 10³ to scientific notation, which is 4 × 10⁴. Now, you can subtract the numbers: (6.515 × 10⁴) - (4 × 10⁴) = 2.515 × 10⁴. The answer in standard form is 25,150.
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