How do I solve part b of the question
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[tex](p - q)(p + 2q) = 61 \\ \Leftrightarrow p - q = 1 \: \wedge \: p + 2q = 61 \: or \: p - q = 61 \: \wedge \: p + 2q = 1 \\ \Leftrightarrow p = 21\: \wedge \:q = 20 \: or \: p = 41\: \wedge \:q = - 20 \: (rule \: out \: because \: q > 0) \\ \Rightarrow p = 21\: \wedge \:q = 20[/tex]