When the Mishkan was first put up the leaders of the 12 tribes each brought animals and other gifts to the Mishkan. Among the gifts were 12 silver bowls and 12 silver basins. The total weight of all the bowls and basins was 2,400 shequels. Each silver bowl weighted 130 shequel. (Bamidbar 7:85) What was the weight of each silver basin?
[(total weight of all bowls and basins) – (number of bowls) x (weight of each bowl)] / (number of basins) = (weight of each basin)
12 bowls x 130 shequels = 1,560 shequels (total weight of all the bowls)
2,400 – 1,560 = 840 shequels (total weight of the basins)
840 / 12 = 70 shequels (weight of each basin)