Question 1177029
Not sure if assigning a variable to "what percentange did Ann take" is the easiest or best way, but


b, number of biscuits initially in the jar


<pre>
PERSON           BISCUITS TAKEN
Kate               0.3b
Melissa            0.25b
Jack              80
Ann                0.25b+20
SUM                 b
</pre>
Solve this equation to find how many biscuits were in the jar at the start:
{{{0.3b+0.25b+80+(0.25b+20)=b}}}


Once b is found, get Ann's percentage of biscuits according to
{{{100((0.25b+20)/b)}}}.


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500 biscuits in the jar?  Maybe these are small cookies in a very big jar.