Solutions by everydaycalculation.com
521 + 321 is 821.
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 10/21+3/21 5/21+6/21 5/42+3/21 5/21+3/42 15/21+3/21 5/21+9/21 5/63+3/21 5/21+3/63 25/21+3/21 5/21+15/21 35/21+3/21
© everydaycalculation.com