WAEC 2021 · Paper 1 · Q8

What number should be subtracted from the sum of $2\frac16$ and $2\frac{7}{12}$ to give $3\frac14$ ?

Worked solution (try it first)

Add the two numbers.
The LCD of 6 and 12 is 12: $2\frac{2}{12} + 2\frac{7}{12} = 4\frac{9}{12}$
$= 4\frac34$ .
The number is what you take from $4\frac34$ to leave $3\frac14$ : $4\frac34 - 3\frac14 = 1\frac24 = 1\frac12$ , option B.