No. AB is not perpendicular to AC
60 is the base OK. I think am right
12.5 gallons..............
Greetings from Brasil...
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Here's our problem:

From potentiation properties:
Mᵃ ÷ Mᵇ = Mᵃ⁻ᵇ
<em>division of power of the same base: I repeat the base and subtract the exponents</em>
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Bringing to our problem
12¹⁶ ÷ 12⁴
12¹⁶⁻⁴
<h2>12¹²</h2>
the volume is 288 for the prism