WAEC Mathematics 2016 Paper

Concept:Solve the simultaneous equations by substitution, then find the value of $7x - 10$.Explanation:Given the equations:$2x + y = 7$ ... (1)$3x - 2y = 3$ ... (2)From equation (1), express $y$ in terms of $x$:$y = 7 - 2x$Substitute $y = 7 - 2x$ into equation (2):$3x - 2(7 - 2x) = 3$Expand the bracket:$3x - 14 + 4x = 3$Combine like terms:$7x - 14 = 3$Add $14$ to both sides:$7x = 17$Now, the question asks by how much $7x$ is greater than $10$.So compute $7x - 10$:$7x - 10 = 17 - 10 = 7$Answer:$7$Therefore, the correct option is C.