设为a
16.2×〔(4又7分之1减去几÷1又2/7)÷1又7分之2〕=8.1
16.2×(29/7 - 7/9 a)×7/9=8.1
81/5×7/9×(29/7- 7/9 a )=81/10
29/7- 7/9 a=81/10×5/63
a=9/2
设为a
16.2×〔(4又7分之1减去几÷1又2/7)÷1又7分之2〕=8.1
16.2×(29/7 - 7/9 a)×7/9=8.1
81/5×7/9×(29/7- 7/9 a )=81/10
29/7- 7/9 a=81/10×5/63
a=9/2