Find the value of a so that the equation  x - y = a  may have x = 1, y = 1 as a solution

40 Find four solutions for the following equation: x = 0. 41 Find the solutions of the form x = a, y = 0 and x = 0, y = b for each of the following pairs of equations. 
         Do they have any common such solution?
         (i)   3x + 2y = 6 and 5x - 2y =10
         (ii)  5x + 3y = 15 and 5x + 2y =10
         (iii) 9x + 7y = 63 and x - y =10 43 Draw the graph of the following equation: x = 2 44 Draw the graph of the following equation: y = 3