Answer:
16 kg
Explanation:
Mass = (5x - 4) kg
Unit Price = 3x/kg
Total Price = mass * unit price
Total Price = (5x - 4)kg * 3x/kg
Total Price = 15x^2 - 12x
Total Price = 192
15x^2 - 12x = 192
15x^2 - 12x - 192 = 0
5x^2 - 4x - 64 = 0
ax^2 + bx +c = 0
ac = 5(-64) = -320
ac = -20 * 16
-20 + 16 = -4
5x^2 - 20x + 16x - 64 = 0
5x(x - 4) + 16(x - 4) = 0
(x - 4)(5x + 16) = 0
x - 4 = 0 or 5x + 16 = 0
x = 4 or 5x = -16
x = 4 or x = -3.2
x cannot be negative because it would give a negative unit price, so we discard the negative answer.
x = 4
mass = 5x - 4 = 5(4) - 4 = 20 4 = 16
Answer: 16 kg