Please solve

The marketing departments of a toy company has determined that t weeks after an advertising campaign ends, the number N of the advertised toys it sells each month decreases according to the exponential decay function N(t) = 2,600e -0.13t. To the nearest whole number, find how many of the advertised toys the company will sell a. immediately at the close of the advertising campaign. toys b. one week after the end of the campaign. toys c. five weeks after the end of the campaign. toys d. 12 weeks after the end of the campaign. toys