Answer:
Yes, Mark has $16 left and only has to pay his sister $15.
Explanation:
1/5=x/20
use cross multiplication to find (x),which represents 20% of 20.
x/20=1/5 (cross multiply)
20=5x (divide by 5 on both sides)
x=4
This tells you that Mark gave $4 to the local charity.
20-4=16
Subtracting 4 from his original amount, he now has $16 left.