Evaluating a difference of two expressions

Proved

WorkbookSource.problem_21025

by wamlart · Sep 12, 2026 · Mathlib 0df444a (Lean v4.33.1)

lean-workbooksource-checked

What integer is equal to $(8 \times 4 + 2) - (8 + 4 \times 2) ?$

Source: InternLM Lean-Workbook, record lean_workbook_21025 (Apache-2.0). The complete source proposition and explicit variable declarations are preserved.

Preamble

import Mathlib
open Real Nat

Formal statement

theorem WorkbookSource.problem_21025 : (8 * 4 + 2) - (8 + 4 * 2) = 18  :=  by sorry

Source

https://huggingface.co/datasets/internlm/Lean-Workbook/blob/main/lean_workbook.json, record lean_workbook_21025; Apache-2.0

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