Answer:
a) 4 packages
b) 7000 g or 7 kg
Step-by-step explanation:
x is the number of 250g packages and y is the number of 750g packages.
2x = y
3(x + 2 x (750 : 250)) = 5(y - 2)
3(x + 6) = 5(y - 2)
3(x + 6) = 5(2x - 2)
3(x + 6) = 5(2(x - 1))
3(x + 6) = 5 * 2 * (x - 1)
3(x + 6) = 10(x - 1)
3x + 18 = 10x - 10
(3x + 18) + 10 = (10x - 10) + 10
3x + 28 = 10x
28 = 10x - 3x
28 = 7x
x = 28/7
x = 4
y = 2 * 4 = 8
(250 * 4) + (750 * 8) = 7000 g