k x [a / b x {c x d / (e x f)}]

The same question, asked 2 times: 17 Jul 2023 S1*, 23 Sep 2024 S1. Every wording below, oldest first.

Try each one first, then open its answer.

Question 1
17 Jul 2023 S1
51 $2.5 \times [144 \div 198 \times \{121 \times 81 \div (11 \times 9)\}]$
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Question 2
23 Sep 2024 S1
57 $6 \times [28 \div 84 \times \{36 \times 49 \div (6 \times 7)\}]$
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