解:5÷(X+16.81)=
,
5÷(X+16.81)×(X+16.81)=
×(X+16.81),
×(X+16.81)=5,
×(X+16.81)×5=5×5,
X+16.81=25,
X+16.81-16.81=25-16.81,
x=8.19.
分析:根据等式的性质,两边同乘(X+16.81),得
×(X+16.81)=5,两边同乘5,再同减去16.81即可.
点评:此题考查了根据等式的性质解方程,即等式两边同加、同减、同乘或同除以一个数(0除外),等式的左右两边仍相等;注意等号上下要对齐.