What is the value of x in following equation?  

​$$8.5-[5\frac{ 1}{2}-(7 \frac{1}{2}+2.8÷x)]×4.25÷(0.2)^2=306$$  

Correct option is B

Given:

$$8.5-[5\frac{ 1}{2}-(7 \frac{1}{2}+2.8÷x)]×4.25÷(0.2)^2=306$$  

Solution:

​$$-[5\frac{ 1}{2}-(7 \frac{1}{2}+2.8÷x)]×4.25÷(0.2)^2=306 - 8.5$$ 

(- 5.5  + 7.5 + 2.8 ÷x)]$$\frac{425}{4}$$  = 297.5

 2 + 2.8÷x) = $$\frac{1190}{425}$$ 

 2.8÷x  = $$\frac{1190}{425} - 2$$ 

2.8 ÷x = $$\frac{1190 - 850}{425}$$ 

2.8÷ x = $$\frac{340}{425}$$ 

 x = $$\frac{425\times2.8}{340} = 3.5$$​​

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