The consumer price index, C, depends on the current value of gross regional domestic expenditure E, number of people living in poverty P, and the average number of household members in a family F, according to the formula: e-EP C = 100+ F It is known that the gross regional domestic expenditure is decreasing at a rate of PHP 50 per year, and the number of people living in poverty and the average number of household members in a family are increasing at 3 and 1 per year, respectively. Use total differential to approximate the change in the consumer price index at the moment when E= 1,000, P=200, and F= 5.