65.0
This is because 4 is not a big enough number to round up, so you must round down. When it is 5 and over, you can round up.
Answer is a Decimal: x=-0.4
a. A' means the complement with respect to Z? If so, then
To know A' you need to write all the elements in Z that are not in A.
b. All the subsets of B, is knowed as P(B),
c. 
(Add to A the elements of B, or equivalently add to B the elements of A)
d. 
express informally speaking the elements that have in common, but there is no element in common, so
The value of t is 3/2 or 1.5
<u>Step-by-step explanation</u>:
The given expression is 17/20 equals t plus -13/20.
<u>Changing it into an equation form :</u>
⇒ t + (-13/20) = 17/20
Keeping t alone on one side and constant terms to the another side,
t = (17/20) + (13/20)
Since the denominators are same, it is easy to simplify those fractions.
⇒ t = (17+13)/20
⇒ t = 30/20
⇒ t = 3/2
⇒ t = 1.5
The solution is t= 3/2 or t= 1.5
