13.289. There are two alloys consisting of zinc, copper, and tin. It is known that the first alloy contains $40 \%$ tin, and the second - $26 \%$ copper. The percentage of zinc in the first and second alloys is the same. By melting 150 kg of the first alloy and 250 kg of the second, a new alloy was obtained, in which there turned out to be $30 \%$ zinc. How much tin is contained in the newly obtained alloy?