A batch of goods, according to 1:4:5 to a, B, C three motorcade to transport, when the end of the transport, B for a total of 12 tons of goods, a, C two

A batch of goods, according to 1:4:5 to a, B, C three motorcade to transport, when the end of the transport, B for a total of 12 tons of goods, a, C two

Primary school mathematics? But from your question, you can only have the following results:
With 12 / 4 of B = 3 tons, 1 * 3 of a = 3 tons, and 5 * 3 of C = 15 tons, a and C transported 3 tons and 15 tons respectively, and a, B and C transported 30 tons in total

Party A and Party B transport a batch of goods together. At the end of the transport, Party A has transported more than 12 tons, 7 / 15 of the total, 1 / 2 more than Party B. how many tons are there in total
Formula

Total number × 7 / 15 + 12 = a
B × (1 + 1 / 2) = a
B × (1 + 1 / 2) + B = total = 2.5 × B
2.5 × B × 7 / 15 + 12 = B × (1 + 1 / 2)
B = 36
A = 54
Total = 90
Let B be y
(y＋3/2y)×7/15＋12=3/2y
y=36