Please help

The function S(t) = 2.5 . 3 models the growth of a tumor where t is the number of months since the tumor was discovered and S is the size of the tumor in cubic millimeters. The size of the tumor when it was discovered was 2.5 cubic millimeters. Find the total change in the size of the tumor in the first 4 months and find the average rate of change in the size of the tumor in the first 4 months. The total change in size of the tumor in the first 4 months was cubic millimeters. The average rate of change of the tumor in the first 4 months was cubic millimeters per month. ( Do not round. )