Solutions by everydaycalculation.com
421 - 721 is -17.
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 8/21-7/21 4/21-14/21 4/42-7/21 4/21-7/42 12/21-7/21 4/63-7/21 4/21-7/63 20/21-7/21 4/21-35/21 28/21-7/21 4/21-49/21
© everydaycalculation.com