Given the word problem, we can deduce the following information:
1. Liz collected 16 cans, which is 20% of her goal.
To determine the number of cans that Liz needs to collect to reach her goal, we use below equation:

where:
x= total number of cans that Liz needs to collect
So,

Hence, the total number of cans is 80.
A.
To complete the double number line, we must determine first the other percent values. It the goal is 100%, we must subtract 20% from 100% and divide it by 4 to get the remaining percent values. So,

So the other percent values are:
0%
20%
20%+20%=40%
40%+20%=60%
60%+20%=80%
80%+20%=100%
To determine the amount of cans for each percent value,the process is shown below:




Therefore, the answer for double number line is:
Cans : 0 16 32 48 64 80
Percent : 0% 20% 40% 60% 80% 100%
B.
Based on the information gathered from A, for every 16 cans Liz collects, she adds 20% toward her goal. She will have 32 cans if she reaches 40% of her goal. Liz must collect 80 cans to reach her goal.