Answer:
$51.50
Step-by-step explanation:
Let the amount that Phil give to her sister be [tex]x[/tex]
After Phil's sister pays her debt of 10, Phil and her sister should have EQUAL amount. So we can write the equation as:
[tex]93-x=x-10[/tex]
Now solving this for x, we have:
[tex]93-x=x-10\\93+10=x+x\\103=2x\\x=\frac{103}{2}=51.5[/tex]
Hence, Phil must give $51.50 to her sister.