To solve this problem you must apply the proccedure shown below:
1. You have that Addison whines 2 minutes for every 3 minutes Wyatt whines. And they whine a total of 45 minutes. Therefore, you can make the following system of equations, where [tex]x[/tex] is the minutes that Wyatt whines and [tex]y[/tex] the minutes that Addison whines:
[tex]\left \{ {{x=\frac{3}{2}y } \atop {x+y=45}} \right.[/tex]
2. You can solve it by the Method of subtitution:
[tex]x+y=45[/tex]
[tex]\frac{3}{2}y+y=45[/tex]
[tex]\frac{5}{2}y=45[/tex]
[tex]y=18[/tex]
3. Now, calculate [tex]x[/tex]
[tex]x+18=45[/tex]
[tex]x=27[/tex]
Therefore, the answer is: Addison whined for 18 minutes.