Answer:
Number of small candles = 12
Number of large candles = 16
Step-by-step explanation:
Total candles = 28
x + y = 28 ---------------(I)
Cost of 'x' small candles = 4 *x = 4x
Cost of 'y' large candles = 6 *y = 6y
Total amount = $144
4x + 6y = 144 -------------(II)
Multiply equation (I) by (-4) and then add the equation. So, x will be eliminated and we can find the value of 'y'
(I) * (-4) -4x - 4y = -112
(II) <u> 4x + 6y = 144</u> {Now, add}
2y = 32
y = 32/2
y = 16
Plug in y = 16 in equation (I)
x + 16 = 28
x = 28 - 16
x = 12
Answer: The average was 9 years old find the average age of both groups is 10 years old.
Step-by-step explanation:
Formula foe average : 
Given : The first group of students consists of 10 and their average age was 13 years old.
i.e.
(1)
The next group consisted of 30 students and their average was 9 years old.
i.e.
(2)
Then from (1) and (2) , the sum of both groups (first group and next group )students = 130+270 =400
Combined students of both groups (first and next group )= 10+30=40
Now , the average of both groups =

Hence, the average was 9 years old find the average age of both groups is 10 years old.
40 divides by 31 = 1.29 which is 1 1/3 cup per day
1.29 x 6 days = 7.74 cans
About 7 3/4 cans in 6 days
15 tablespoons of sugar is needed for 10 people
3 becuse you put the numbers wrong