How do you know if a value is a solution for an inequality? 
Substitute the value for the variable and see if it leads to a true inequality.
How is this different from determining if a value is a solution to an equation? 
It isn't. Substitute the value for the variable and see if it leads to a true equation.
If you replace the equal sign of an equation and put an inequality sign in its place, is there ever a time when the same value will be a solution to both the equation and inequality?
Yes, but only sometimes when the inequality sign is  or
 or  but never when the inequality sign is
 but never when the inequality sign is  ,
,  or
 or  .
Edwin
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Edwin