if we assume that she had exactly 200 dollars
mone per shirt times amount of shirts=amount spent
if we assume that she spend 200 dollars then
15 times ?=200
divide both sides by 15
?=13.3333333333333
if she had spent 200 exactly she could have bought 13.333 shirts
you can't buy 0.3333 shirt so round down
13 shirts bought
that is assuming she had at least 195 to spend
if she spent 0 dollars (which is less than 200) then she bought 0 shirts, that is also possible
max number of possible shirts is 13
