9а + 3а + 8b + 4b = 12a + 12b = 12*(a + b),
если а + b = 6, то 12*(a + b) = 12 * 6 = 72
14c + 5d + 13c + 22d = 27c + 27d = 27*(c + d),
если c + d = 4, то 27*(c + d) = 27 * 4 = 108
7x + 8y + 11y + 12x = 19х + 19у = 19*(х + у),
если x + y = 3, то 19*(х + у) = 19 * 3 = 57
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