Ratio and Proportion

Concept:Use the ratio of remaining baskets to find the common multiplier, then calculate the initial number in the third truck.Explanation:Let the initial baskets in the three trucks be $a$, $b$, $c$.Given $a + b + c = 1230$.After removing rotten baskets: $a-5$, $b-10$, $c-15$ are in the ratio $3:4:5$.Let the common multiplier be $k$.Then: $a-5 = 3k$, $b-10 = 4k$, $c-15 = 5k$.So $a = 3k + 5$, $b = 4k + 10$, $c = 5k + 15$.Sum: $(3k+5) + (4k+10) + (5k+15) = 12k + 30 = 1230$.Solving: $12k = 1200 \Rightarrow k = 100$.Thus $c = 5 \times 100 + 15 = 515$.Initial baskets in the third truck = 515.Answer:515