138+69*284+31*286
=69*2+69*284+31*286
=69*(2+284)+31*286
=69*286+31*286
=(69+31)*286
=100*286
=28600
138+69乘284+31乘286=?是简便运算.
138+69*284+31*286
=69*2+69*284+31*286
=69*(2+284)+31*286
=69*286+31*286
=(69+31)*286
=100*286
=28600