(5a + 18) + (48 - a) + (8a - 30) = 180
5a + 18 + 48 - a + 8a - 30 = 180
5a - a + 8a + 18 + 48 - 30 = 180
12a + 36 = 180
12a = 180 - 36
12a = 144
a = 12
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