In \( \triangle ABC \), \( DE \parallel AB \), \( AD = x + 1 \), \( CD = x + 3 \), \( BE = x + 4 \) and \( CE = x + 7 \), then the value of \( x \) is _____.
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After solving BPT problems, always verify by substituting the value back into both ratios. It quickly confirms correctness and avoids careless mistakes in exams.