in a group of 59 traders, 26 sell gari, eight (8) sell only rice, and 15 sell only maize. ten (10) sell gari and rice, 16 sell rice and maize, and 42 sell maize. each trader sells at least one of the three items. find the number of traders who sell: (a) gari or maize, (b) gari and maize, (c) only two items.​