Answer:
750 sheets
Step-by-step explanation:
2.5 kilograms=2.5*1000=2500 grams
2500/40=62.5 stacks-of-12-papers
62.5*12=750 sheets of paper
To check our work: 
Let's set x as the weight of one sheet of paper.
12x=40 grams, x= 3 1/3 (three and one thirds) grams
3 and 1/3 *750= 2500 grams
2500 grams=2.5 kilograms
 
        
             
        
        
        
<h3><u>Question:</u></h3>
The rectangle below has an Área of x^2 + 11x + 28 square meters and a length of x+7 meters. What expression represents the width of the rectangle?
<h3><u>Answer:</u></h3>
The expression representing width of rectangle is (x + 4) meters
<h3><u>Solution:</u></h3>
Given that rectangle has an area x^2 + 11x + 28 square meters and a length of x + 7 meters
To find: width of the rectangle
<em><u>The area of rectangle is given as:</u></em>

Here area = x^2 + 11x + 28 square meters
length = x + 7 meters
<em><u>Substituting the values in given formula,</u></em>

Cancelling (x + 7) on numerator and denominator,

Thus expression representing width of rectangle is (x + 4) meters
 
        
        
        
Answer:
3 groups
Step-by-step explanation:
Sopranos = 12
Altos = 9
Find the highest common factor of 12 and 9
12 = 1, 2, 3, 4, 6, 12
9 = 1, 3, 9
The highest common factor of 12 and 9 is 3
Therefore, the choir teacher can only have 3 groups
12 sopranos / 3 groups 
= 4 sopranos per group
9 Altos / 3 groups
= 3 altos per group
Each of the 3 groups Will have 4 sopranos and 3 altos each
 
        
             
        
        
        
Any rectangle has two equal sides, so any rectangle you draw will be right