The common denominator would be 18. So, 5/6 becomes 15/18 and 7/9 becomes 14/18
Step-by-step explanation:
1) -9 = 9 true/false
the answer is false because negative and positive quite unlike in terms.
2) -(-21) = -21
Using the symbols multiplication rule,
Where,
<h2>
+ × + = +</h2><h2>
- × - = +</h2><h2>
- × + = -</h2><h2>
+ × - = -</h2>
Therefore, -(-21) = +21 = 21
⟼ 21 = -21 
Let us assume the number of student's in Zoe's class = x
Then
Number of students that have pets = 4x/5
Number of students that have rodents as pets = (1/8) * (4x/5)
= x/10
Number of students in Zoe's class
that have pets that are not rodents = (4x/5) - (x/10)
= (8x - x)/10
= 7x/10
I hope that the procedure is clear enough for you to understand and this is the answer that you were looking for.
1/2 t-4(2+t)=20
1/2 t-8-4t=20
least common multiple=2
t-16-8t=40
-7t=40+16
-7t=56
t=56/-7=-8
Answer: t=-8
To check
-8/2 - 4(2-8)=-4-4(-6)=-4+24=20