(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
1.5a=300
a=200