(a+300)÷a=2.5 求a?

(a+300)÷a=2.5 --> (a÷a)+(300÷a)=2.5 --> 1+(300÷a)=2.5 -->300÷a=2.5-1 =1.5=3/2 --> a/300 = 2/3 -->a=200 ..ans

a+300=2.5a

300=2.5a-a

300=1.5a

200=a

(a+300)÷a=2.5
a+300=2.5a
1.5a=300
a=200