Add: 14 + 27 = 1 · 74 · 7 + 2 · 47 · 4 = 728 + 828 = 7 + 828 = 1528
The common denominator you can calculate as the least common multiple of the both denominators - LCM(4, 7) = 28Add: 1528 + 12 = 1528 + 1 · 142 · 14 = 1528 + 1428 = 15 + 1428 = 2928
The common denominator you can calculate as the least common multiple of the both denominators - LCM(28, 2) = 28