80% of 20 is 80/100 x 20 = 16
So, kelly has used 16 stamps, and has 4 left
Idk if this really helps, but I put them into Desmos (free graphing thing) and this popped up
Answer:
x=
Step-by-step explanation:
2x +2/3=5
x=13/6
The first one because the left bound is included [ and the right one is not )