To simplify the expression \((3r \cdot 5) \cdot (-3 \cdot 8)\), we can break it down step by step.
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First, let's calculate what's in the first parentheses: \[ 3r \cdot 5 = 15r \]
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Next, we calculate what's in the second parentheses: \[ -3 \cdot 8 = -24 \]
Now that we have these results, we can rewrite the expression: \[ (3r \cdot 5) \cdot (-3 \cdot 8) = 15r \cdot (-24) \]
Now, let's multiply \(15r\) by \(-24\): \[ 15r \cdot (-24) = -360r \]
So, the final answer is: \[ \boxed{-360r} \]