10+21-32+43-54+65-76+87-98+109=
问题描述:
10+21-32+43-54+65-76+87-98+109=
答
=31-32+43-54+65-76+87-98+109
=-1+43-54+65-76+87-98+109
=42-54+65-76+87-98+109
=-2+65-76+87-98+109
=63-76+87-98+109
=-13+87-98+109
=74+87-98+109
=161-98+109
=63+109
=172