If the average of 16x and 8y is greater than 80, and x is twice y, what is the least integer value of x ? Choose the correct choice.
A) 8  B) 9  C) 10  D) 11  E) 12
Substitution can be used in the following way:   Always start with the equation: x = 2y. It is more straight forward to manage as compared to the inequality.   Substitute y = x/2, not the other way because you need to find the minimum value of x. So you can get rid of y.   Now go on to the inequality. So 8y = 8x/2 = 4x   Now average of 16x and 4x is greater than 80. Average of 16x and 4x is 10x. So,   10x &gt; 80   x &gt; 8   8nswer : 88 /2= 
<gadget id="calculator">8 /2</gadget>
<output>4</output>
4x   Now average of 16x and 4x is greater than 80. Average of 16x and 4x is 10x. So,   10x &gt; 80   x &gt; 8   8nswer : 8
<result>A</result>
If the average of 16x and 8y is greater than 80, and x is twice y, what is the least integer value of x ?