<img src="https://tex.z-dn.net/?f=5L%20%2B%207C%20%3D%20109%0A" />
<img src="https://tex.z-dn.net/?f=8L%20%2B%2011C%20%3D%20173%0A" />
<img src="https://tex.z-dn.net/?f=5L%20%3D%20109%20-%207C" />
<img src="https://tex.z-dn.net/?f=L%20%3D%20%5Cfrac%7B109-7C%7D%7B5%7D%20" />
<img src="https://tex.z-dn.net/?f=8L%3D173-11C" />
<img src="https://tex.z-dn.net/?f=L%3D%20%5Cfrac%7B173-11C%7D%7B8%7D%20" />
<img src="https://tex.z-dn.net/?f=%5Cfrac%7B109-7C%7D%7B5%7D%3D%20%5Cfrac%7B173-11C%7D%7B8%7D" />
<img src="https://tex.z-dn.net/?f=%5Cfrac%7B109%7D%7B5%7D-%20%5Cfrac%7B7C%7D%7B5%7D%20%3D%20%5Cfrac%7B173%7D%7B8%7D-%20%5Cfrac%7B11C%7D%7B8%7D%20" />
<img src="https://tex.z-dn.net/?f=-%20%5Cfrac%7B7C%7D%7B5%7D%2B%5Cfrac%7B11C%7D%7B8%7D%20%20%3D%20%5Cfrac%7B173%7D%7B8%7D-%5Cfrac%7B109%7D%7B5%7D" />
<img src="https://tex.z-dn.net/?f=-%20%5Cfrac%7B7C%2A8%7D%7B5%2A8%7D%2B%5Cfrac%7B11C%2A5%7D%7B8%2A5%7D%20%20%3D%20%5Cfrac%7B173%2A5%7D%7B8%2A5%7D-%5Cfrac%7B109%2A8%7D%7B5%2A8%7D" />
[img = 10]
[img = 11]
[img = 12]
[img = 13]
[img = 14]
[img = 15]
5L + 7C = 109
5L = 109 - 7(7)
5L = 109 - 49
5L = 60
L = 60 / 5
L = 12
UN CUADERNO VALE $7 Y UN LIBRO VALE $12.