Given: Equations 2x + 3y = 20 and x – 2y = 3 intersects at P(x1, y1) Equation x – 2y = 8 intersects the x-axis at Q(x2, y2) Calculation: We have, 2x + 3y = 20 ----(1) x – 2y = 3 ----(2) x – 2y = 8 ----(3) Here, equation (1) and (2) intersect each other, Multiply equation (2) by 2 and subtract the resultant from equation (1), we get 3y + 4y = 20 - 6 ⇒ y = 2 ----(4) Put the value of equation (4) in (2), we have x - (2 × 2) = 3 ⇒ x = 3 + 4 ⇒ x = 7 So, P(x1, y1) = (7, 2) Now, equation (3) intersect at x-axis So, y = 0 Put the value of y = 0 in equation (3), we get x - (2 × 0) = 8 ⇒ x = 8 So, Q(x2, y2) = (8, 0) Now, x1 – x2 + y1 + y2 ⇒ 7 - 8 + 2 + 0 ⇒ 1 ∴ The value of x1 – x2 + y1 + y2 is 1.