Answer:
She began with $15.
Step-by-step explanation:
Let Ming-li has $x to spend.
She spent $15 at the movies.
Net balance = $(x - 15)
She spent $12 at the book store.
Balance amount = $(x - 15) - 12
She earned $30 by babysitting.
Net amount she had = $[x - 15 - 12 + 30]
= $(x + 3)
She is now left with the total amount = $18
Therefore, the expression will represent the amount left will be
(x + 3) = 18
x = 18 - 3
x = $15
She began with $15.
