12分之5乘4.69加3.21乘10又12分之5加7.9除以1又7分之5是多少
问题描述：
12分之5乘4.69加3.21乘10又12分之5加7.9除以1又7分之5是多少
答
原式=5/12x4.69+3.21x{10(5/12)}+7.9÷{1(5/7)}
=5/12X4.69+(10+5/12)X3.21+ 7.9X 7/12
=5/12X4.69+32.1+(5/12)X3.21+7.9 X 7/12
=5/12 X (4.69+3.21) +32.1+7/12 X7.9
=5/12 X 7.9 +32.1 +7/12 X7.9
=7.9X(5/12+7/12)+32.1
=7.9X1+32.1
=40