20 + 20 + 20 + 20 + 20 + 30 + 30 +30 + 30 + 30=?
20 + 20 + 20 + 20 + 20 + 30 + 30 + 30 + 30 + 30
=20 x 5 + 30 x 5
=100 + 150
=250
Math You Like 09/09/2017 at 15:48