What does %d, , %c, %s mean and what's their difference?

Least square fit to polynomial write a function leastsquarefit3pol that solves a linear system of equations to find a least squares fit of a third order polynomial to an experimental data set given as two row arrays. the function leastsquarefit3pol must explicitly solve a set of linear equations and cannot use polyfit. there should be no restriction on the size of the problem that can be solved.

To check whether your writing is clear , you can

Which of the following is not a key player in the sale of travel products?