3.5×1.25+1.25+3.5÷0.8
=3.5×1.25+1.25+3.5×1.25
=1.25×(3.5+1+3.5)
=1.25×8
=10
9/20÷[ 1/2×(2/5+4/5)]
=9/20÷【1/2×6/5】
=9/20÷3/5
=9/20×5/3
=(9×5)/(20×3)
=3/4
3.5×1.25+1.25+3.5÷0.8
=3.5×1.25+1.25+3.5×1.25
=1.25×(3.5+1+3.5)
=1.25×8
=10
9/20÷[ 1/2×(2/5+4/5)]
=9/20÷【1/2×6/5】
=9/20÷3/5
=9/20×5/3
=(9×5)/(20×3)
=3/4