WAEC 2024 · Paper 1 · Q17

A number is added to both the numerator and the denominator of the fraction $\frac18$ . If the result is $\frac12$ , find the number.

Worked solution (try it first)

Call the number $x$ : $\dfrac{1 + x}{8 + x} = \dfrac12$ .
Cross-multiply: $2(1 + x) = 8 + x$ , so $2 + 2x = 8 + x$ .
Take $x$ and 2 from both sides: $x = 6$ , option D.
Check: $\frac{7}{14} = \frac12$ .

Report a problem with this question