Final answer:
To find the number of kilos the junk shop should pay for an amount of 390 pesos, set up a proportion by equating the cost of each kilogram to the weight of the tin cans.
Step-by-step explanation:
The weight of the recycled tin cans is directly proportional to the cost of the cans. This means that as the weight increases, the cost also increases. Let's say the weight of the tin cans is w kilograms and the cost of each kilogram is 60 pesos. To find the number of kilos the junk shop should pay for an amount of 390 pesos, we can set up a proportion:
w / 60 = 390 / 1
Cross multiplying, we get:
w = (390 x 60) / 1
w = 23400 / 1
w = 23400
Therefore, the junk shop should pay for 23400 kilos of tin cans.