Mary bought \(3\dfrac{1}{2}\) m of lace. She used \(1\dfrac{3}{4}\) m. How much lace is left?
\(1\dfrac{3}{4}\,\text{m}\)
We need to find: total lace − used lace.
Write the mixed numbers as improper fractions.
\(3\dfrac{1}{2}\): \(3\times 2 = 6\), then \(6+1=7\).
So, \(3\dfrac{1}{2} = \dfrac{7}{2}\).
\(1\dfrac{3}{4}\): \(1\times 4 = 4\), then \(4+3=7\).
So, \(1\dfrac{3}{4} = \dfrac{7}{4}\).
Make denominators the same (LCM of 2 and 4 is 4).
\(\dfrac{7}{2} = \dfrac{14}{4}\).
Now subtract the fractions.
\(\dfrac{14}{4} - \dfrac{7}{4} = \dfrac{7}{4}\).
Change \(\dfrac{7}{4}\) back to a mixed number.
\(\dfrac{7}{4} = 1\dfrac{3}{4}\).
Lace left = \(1\dfrac{3}{4}\,\text{m}\).