If [tex]\frac { 3 }{ 4 } [/tex] is left, that means [tex]\frac { 1 }{ 4 } [/tex] was spent. So [tex]\frac { 1 }{ 4 } [/tex] of the total amount is equal to 39.. Let's say x to the total amount. [tex]\frac { 1 }{ 4 } \cdot x=39\\ x=4\cdot 39\\ x=156\\ [/tex]