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1. If 5^a = 3125, then the value of 5^{(a - 3)} is:

A. 25

B. 125

C. 625

D. 1625

Solution:

5^a = 3125 ⇔ 5^a = 5⁵
⇒ a = 5.
∴ 5^{(a - 3)} = 5^{(5 - 3)} = 5² = 25