What is the solutionto the linear equation? d-10-2d+7=8+d-10-3d

Last year amusement park received 236,758 visitors it was open every day of the year but 7 holliday’s what was the average number of visitors to the park per day

What is the size of the matrix resulting from

How many sides does a regular polygon have if each exterior angle measure is 45 degrees explain your answer, i really don't understand this.