In order for Andrea to make profit, the value of the C in the given function must not be 0 or less than zero. So, let's find the value of x when C is zero.
C = 0 = 10x - 50 x = 5
Hence, the number of candles sold represented by x must be more than 5 (< 5). Therefore, the domain is (5,+∞). When the value of x is more than 5, the C or the range would be greater than 0. Thus, the range is (0,+∞).
A=3B 4.35A+5.40B=780.95 Substitute 3B into A for the second equation: 4.35(3B)+5.40B=780.90 13.05B+5.40B=780.90 18.45B=780.90 B=42.33 Plug into equation 1: A=3B A=3(42.33) A=126.98