Answer:
Ivy is 6 years old and Rose is 12 years old.
Step-by-step explanation:
To solve this problem, two variables are necessary since we have two unknown variables: Ivy's age and Rose's age.
Ivy's age will be [tex]x[/tex]
and Rose's age will be [tex]y[/tex]
"Ivy is half as old as her sister":
[tex]x=\frac{y}{2}[/tex]
this will be our fist equation.
"In six years, Ivy will be two-thirds as old as Rose"
in six years Ivy will have [tex]x+6[/tex] years, and Rose will have [tex]y +6[/tex] years, so for this sentence we have the equation:
[tex]x+6=\frac{2}{3}(y+6)[/tex]
this will be our second equation.
Substituting the value of x from the first equation into the second, and solving for y(Rose):
[tex]\frac{y}{2}+6=\frac{2}{3} (y+6)\\\frac{y+12}{2} =\frac{2}{3} (y+6)\\y+12=\frac{4}{3} (y+6)\\3(y+12)=4(y+6)\\3y+36=4y+24\\36-24=4y-3y\\12=y[/tex]
Rose is 12 years old.
and Ivy (using the fist equation):
[tex]x=\frac{12}{2}=6[/tex]
Ivy is 6 years old.