A firm must use 4units of labour and 5units of capitalto produce 1 unit of its output. Its production function can be written as Q(L,K) = min(?L,K). For this firm, (L, K) = (12,?) is an input combination at whichthe MRTSL, Kis undefined. At the input combination (L, K) = (16, 15), the slope of its isoquant is ?