{ a,b,c } d.p { 3,4,5 }
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a + 2b + 3c = 78
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a / 3 = b / 4 = c / 5 = K
a / 3 = K => a = 3 K
b / 4 = K => b = 4 K
c / 5 = K => c = 5 K
3 K + 2 x 4 K + 3 x 5 K = 78
3 K + 8 K + 15 K = 78
11 K + 15 K = 78
26 K = 78
K = 3
a = 3 x 3 = 9
b = 3 x 4 = 12
c = 3 x 5 = 15