No, because she will go over by .57 cents. So she won't be able to buy the gift. You can find the answer by dividing 18 by 7 and adding that answer to 18 to get the amount total you owe including tax.
A short-cut to accurately evaluate the given expression above is using a scientific calculator where one can include integrals and evaluate using limits. In this case, using a calculator, the answer is equal to 0.2679. One can verify this by integrating truly letting 1-x^2 as u and use its du to be substituted in the numerator
