Its quite simple. for every white bucket of paint he uses, he uses 3 buckets of black paint as well. so if he made 24 litres of grey paint then he would have had to use 24 buckets of white paint. but, this might be a trick question because its saying he made 24 "litres" but the unit it started with was "buckets" so it might be trying to trick you because we dont know how much paint is in one "bucket"
Answer:

Step-by-step explanation:
Let n = the number of prints
and C = the total cost.
At the regular price, the formula is
C = 1.45n
During the promotion, you must pay for the first nine prints: 9 × 1.45 = 13.05.
For anything over nine prints (n - 9), you must pay $13.05 plus the promotional cost of $1.10 for each print. The promotional formula is
C = 13.05 + 1.10(n - 9) {n > 9}
1. Calculate the cost of 19 prints

2. What number of the prints is a waste of money?
During the promotion, buying fewer than nine prints would be a waste of money, because you would not be taking advantage of the promotional savings.
Answer:(4,-2)
Step-by-step explanation: elimination method
3(3x+5y)=2×3
9x+11y=14
9x+15y=6
-
9x+11y=14
4y=-8
y=-2
To get x replace y with -2
3x+(5×-2)=2
3×=12
X=4
Answer:90
Step-by-step explanation: