Let the cost of 1 notebook be x and the cost of 1 binder be y.
4 notebooks and 3 binders would cost 23.5
Therefore, 4x + 3y = 23.5 (1)
7 notebooks and 6 binders would cost 44.5
Therefore, 7x + 6y = 44.5 (2)
Multiply the first equation by 2.
8x + 6y = 47 (3)
(3) - (2) gives
x = 2.5
Substitute the value of x in (1), we get,
4(2.5) + 3y = 23.5
10 + 3y = 23.5
3y = 23.5 - 10
3y = 13.5
y = 13.5/3
y = 4.5
Hence, cost of 5 notebooks and 3 binders is:
5x + 3y = 5(2.5) + 3(4.5)
= 12.5 + 13.5
= 26
Hence, cost of 5 notebooks and 3 binders is $26.
Answer: 68
Step-by-step explanation:
Formula for sample size when prior estimate of population proportion (p) is available: 
, where z*= critical-value.
E= Margin of error.
Let p be the population proportion of trees are infected with the citrus red mite.
As per given , we have

E= ± 0.08
The critical z-value corresponding to 90% confidence level = z*=1.645
Substitute all the values in the above formula , we get
Required sample size :

[Rounded to next integer.]
Thus, the minimum sample size should be taken =68
Answer:
20
Step-by-step explanation:
Step-by-step explanation:
18:27
=18/27
=2/3 or 2:3