Answer:
56 trees will make 10000 newspapers.
Step-by-step explanation:
Given:
One tree makes approximately 230 newspapers.
Now, for estimating how many newspapers will be made with 56 trees.
By multiplying 
trees with 
newspapers we get,
.
And, rounding 
to one significant number (1 S.F.) is 
.
Therefore, 56 trees will make 10000 newspapers.
12 oz for 2.68 = .22 per unit
16 oz for 2.49 = .16 per unit
the 16 oz for 2.49 is your better deal
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Let the number be (10 x + y)
Then, 10 x + y = 3 * (x + y) (given)
Or, 10 x + y = 3 x + 3 y
Or, 10 x - 3 x = 3 y - y
Or, 7x = 2 y
Or, x = 2 y / 7 ( Eq. 1)
Also, 10 x + y + 45 = 10 y + x ( given)
Or, 10 x - x = 10 y - y - 45
Or, 9 x = 9 y - 45 ( Eq. 2)
Substituting the value of x from (Eq. 1) in (Eq. 2), we have:
9 * 2 y / 7 = 9 y - 45
Or, (9 y ) - (18 y / 7) = 45
Or, 63 y - 18 y = 315
Or, 45 y = 315
Or, y = 7
From (Eq. 1),
x = 2 * 7 / 7 = 2
So, the number is 10 x + y = (10 * 2) + 7 = (20 + 7) = 27
Answer
Check:
Sum of the digits = 2 + 7 = 9
9 * 3 = 27 ✓
Adding 45 to the number 27, we get 72. So, the digits get reversed.
5x - 15 = 2x - 6
3x = 9
x = 3
Y = 5(3) - 15
Y = 0
(3,0)
