The answer is very simple:
$50 multiplied by 2 (Cause it's 200%) equals to $100
$50 multiplied by 1,2 (Cause it's 120%) equals to $60
Then, you just do the substractions, so you get $40.
Hope I helped u
Total money Tammy has = $70
Money she is left with now = $19.54
Therefore, the money she used on coffee =
70 - 19.54 = $50.46
Now,
1 pound coffee costs $8.41
Pounds of coffee she bought = 50.46 ÷ 8.41
= 6 pounds
I found this :) hope it helps