The largest divisor of 144 is 144 itself, but then \( m + n = 1 \), impossible. Next, try \( d = 72 \): then \( m + n = 2 \), so \( m = n = 1 \), which are coprime. Then \( a = 72 \), \( b = 72 \), and \( \gcd(72, 72) = 72 \). Valid. - Nelissen Grade advocaten