Answer:  Yes.  The pH = 7.6   .
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Explanation:
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pH = - log [H⁺]   ; in which, by convention, we assume that there
                            is an implied "base 10" if there is no number listed as a 
                            "base" under the "log" sign;
i.e. , " pH = - log [H⁺]⁺ = - log₍₁₀₎ [H⁺] ;
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in which, the:  " [H⁺] " refers to the concentration of hydrogen ions, or " H⁺ " ; in "Molarity" ; that is:  "moles of solutes per Liters of solution", or "mol / L", or "M" . 
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Likewise, "pOH = - log [OH⁻] =  - log₍₁₀₎ [OH⁻] " . 
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  Note:  pH  + pOH = 14 .
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So, given:  "A solution with 6.4 * 10⁻¹⁰ M  OH (in our problem), find the "pH".
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   The pOH of the solution is 6.4 .
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Since pH + pOH = 14 ;  
               we can substitute "6.4" for "pOH" ; and solve for "pH":
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      pH + 6.4 = 14 ;
        Subtract "6.4" from each side of the equation; to isolate "pH" on one side of the equation; and to solve for the "pH" ; 
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      pH + 6.4 − 6.4 = 14 − 6.4 ;
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      pH = 7.6   .
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