Steps: (1) Multiply out the brackets on the left handside [11a + 5c = 6d + 2dc]. (2) Put all terms containing c on one side and all other terms on the other side of the equation [ 5c - 2dc = 6d - 11a]. (3) Take c as a factor from the terms that contain c [c(5 - 2d ) = 6d - 11a] (4) Divide through to isolate c by itself [c = (6d - 11a) / (5 - 2d)]