Definition: The task is to generate the correct answer for a given math problem.
Input: Problem: 120 kg of an alloy a is mixed with 180 kg of alloy b . if alloy a has lead and tin in the ratio 2 : 3 and alloy b has tin and copper in the ratio 3 : 5 , then the amount of tin in the new alloy is ?
Output:
139.5 kg