The task is to generate the correct answer for a given math problem.

Problem: the number of positive integer solutions for the equation x + y + z + t = 30 is
3654

Problem: in one alloy there is 12 % chromium while in another alloy it is 8 % . 35 kg of the first alloy was melted together with 40 kg of the second one to form a third alloy . find the percentage of chromium in the new alloy .
9.75 %

Problem: if a person walks at 25 km / hr instead of 10 km / hr , he would have walked 20 km more . the actual distance traveled by him is :

13.3 km