Question 1020238
Princes is P years old now
Kisha is K years old now
</pre>
Princess is two thirds as old as kisha. 

{{{P}}}{{{""=""}}}{{{expr(2/3)K}}}
</pre>
In seven years,
<pre>
In 7 years Princess will be P+7,
and Kisha will be K+7
</pre>
princess will be three fourths as old as kisha.
<pre>
{{{P+7}}}{{{""=""}}}{{{expr(2/3)(K+7)}}}

We have a system of two equations and two unknowns:

{{{P}}}{{{""=""}}}{{{expr(2/3)K}}}
{{{P+7}}}{{{""=""}}}{{{expr(3/4)(K+7)}}}

Simplify each by clearing fractions.
Multiply the first by 3 and the second by 4


{{{3P}}}{{{""=""}}}{{{2K}}}
{{{4P+28}}}{{{""=""}}}{{{3(K+7)}}}

You finish. Princess is a teenager. 
Kisha has just become an adult.

Edwin</pre>