Let the price of a pen be 'x' and that of pencil be 'y' Then 87x + 29y = 783Multiplying eqn (i) by 30/29 we get (87x) x 30/29 + (29y) 30/29 = 783 x 30/29∴ 90x + 30y = 810
Let the four numbers be x, x + 2, x + 4 and x + 6.=> x + x + 2 + x + 4 + x + 6 = 36=> 4x + 12 = 36 => x = 6The numbers are 6, 8, 10 and 12.Sum of their squares = 62 + 82 + 102 + 122 = 36 + 64 + 100 + 144 = 344.