Answer:
She should mix 9 g of powder
Explanation:
From the question, we can have a ratio for powder to water
we have 5 g of powder mixed with 45 cm^3 of water
So, for every 1 g, we have 5g/45 cm^3
we have 9 cm^3
So let’s relate this to the bigger water mix
Recall from above; we have the mixing as 1 g per 9 cm^2 of water
1g per 9 cm^2
x g per 81 cm^2
81 * 1 = x * 9
9x = 81
x = 81/9
x = 9g