Step-by-step explanation:
ATQ,
Let d be the number of kilograms of dark chocolate she buys and m be the number of kilograms of milk chocolate she buys.
She needs to buy 120 kg of chocolate in total for her next order, and her recipe calls for twice the amount of dark chocolate as milk chocolate.
So,
m = 2d .....(1)
m + d = 120 ...(2)
We can also solve the above equations,
Put m = 2d in equation (2)
2d + d = 120
3d=120
d = 40
Put d = 40 in equation (1)
m = 2(40)
m = 80
Hence, she will need 40 kg of dark chocolate and 80 kg of milk chocolate.