We are given that there are 125 boxes. If "x" represents the number of larger boxes and "y" the smaller boxes then this is written mathematically as:
![x+y=125,(1)](https://img.qammunity.org/2023/formulas/mathematics/college/wh95madhjf18lgsbx908fs0ax4x3ud9v2a.png)
We are also given that the larger boxes weigh 45 pounds and the smaller boxes weigh 30 pounds each and the total weight is 4575 pounds. This is written mathematically as:
![45x+30y=4575,(2)](https://img.qammunity.org/2023/formulas/mathematics/college/uh2j7av7dgu3ow57u5yc115f9sh6bp2gsd.png)
We get a system of two equations and two variables. To solve the system we will use the method of elimination. To do that we will multiply equation (1) by -45, we get:
![-45x-45y=-5625](https://img.qammunity.org/2023/formulas/mathematics/college/yd7ebbv98j7061o6i7gf798pdtbzr03v52.png)
Now, we add this equation to equation (2):
![-45x-45y+45x+30y=-5625+4575](https://img.qammunity.org/2023/formulas/mathematics/college/zr2mm9n9h9ebx2149je8wxi389h3jwbhry.png)
Now, we add like terms:
![-15y=-1050](https://img.qammunity.org/2023/formulas/mathematics/college/504hooqnlkiaongz5lmwitx7x3p5ie63jx.png)
Now, we divide both sides by -15:
![y=-(1050)/(-15)](https://img.qammunity.org/2023/formulas/mathematics/college/zbho8gt96ap5sugzyfl8hj5gy5t40t4p0g.png)
Solving the operations:
![y=70](https://img.qammunity.org/2023/formulas/mathematics/college/u84plsa0khexghqlojt4idc0enufk95wbe.png)
Now, we substitute the value of "y" in equation (1):
![x+70=125](https://img.qammunity.org/2023/formulas/mathematics/college/nhuj80sc1h3n4tadysyxsqqu2skh41wo7y.png)
Now, we subtract 70 from both sides:
![\begin{gathered} x+70-70=125-70 \\ x=55 \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/college/utu545se4idwkexkp7vk05lblxwgdlwf0y.png)
Therefore, there are 55 larger boxes and 70 smaller boxes.