Subtract 42/48 from 21/40
21/40 - 42/48 is -7/20.
Steps for subtracting fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 40 and 48 is 240
Next, find the equivalent fraction of both fractional numbers with denominator 240 - For the 1st fraction, since 40 × 6 = 240,
21/40 = 21 × 6/40 × 6 = 126/240 - Likewise, for the 2nd fraction, since 48 × 5 = 240,
42/48 = 42 × 5/48 × 5 = 210/240 - Subtract the two like fractions:
126/240 - 210/240 = 126 - 210/240 = -84/240 - After reducing the fraction, the answer is -7/20
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 42/40-42/48 21/40-84/48 21/80-42/48 21/40-42/96 63/40-42/48