Answer:
680 g
Explanation:
7 rocks ⇒ 5 kg ⇒ 5000g
6 of the rocks each weigh 720g .
So,
The total weight of those 6 rocks is,
6 rocks ⇒ 720 g × 6
⇒ 4320 g
Now you have to find the weight of the other rock.
There fore, let the weight of the other rock be x
x + 4320 = 5000
x = 5000 - 4320
x = 680 g
So, the weight of the other rock is 680 g.
Hope this helps you.