WAEC Mathematics 2013 Paper

Concept:Translate the word problem into a linear equation and solve for the unknown number.Explanation:Let the required number be $x$.Subtracting the number from 2 gives $2 - x$.One-fifth of the number is $\frac{x}{5}$.Four less than this is $\frac{x}{5} - 4$.So the equation is:$$2 - x = \frac{x}{5} - 4$$Add 4 to both sides:$$6 - x = \frac{x}{5}$$Add $x$ to both sides:$$6 = \frac{x}{5} + x$$Combine the terms on the right:$$6 = \frac{6x}{5}$$Multiply both sides by 5:$$30 = 6x$$Divide both sides by 6:$$x = 5$$Check: $2 - 5 = -3$, and $\frac{5}{5} - 4 = 1 - 4 = -3$.Answer:$x = 5$Correct option: C. $5$