-(4  1/5)
5(4)+1 = 21
Thus the answer would be -21/5
        
                    
             
        
        
        
Answer:
x = 13 ; x = 5
Step-by-step explanation:
The easiest related equation to get is simply solving for x: 
a) x + 5 = 18
Isolate the variable, x. Note the equal sign, what you do to one side, you do to the other. Subtract 5 from both sides: 
x + 5 (-5) = 18 (-5)
x = 18 - 5
x = 13*
b) 66x = 330
Isolate the variable, x. Divide 66 from both sides of the equation: 
(66x)/66 = (330)/66
x = 330/66
x = 5*
*Note: An equation simply is a expression that has an equal sign. This means that as long as there is an equal sign, it counts as an equation. 
~
 
        
             
        
        
        
Answer:
87°
Step-by-step explanation:
it can be seen directly
if you want angle AOD
it's 78°
 
        
                    
             
        
        
        
Answer:
There are 165 ways to distribute the blackboards between the schools. If at least 1 blackboard goes to each school, then we only have 35 ways.
Step-by-step explanation:
Essentially, this is a problem of balls and sticks. The 8 identical blackboards can be represented as 8 balls, and you assign them to each school by using 3 sticks. Basically each school receives an amount of blackboards equivalent to the amount of balls between 2 sticks: The first school gets all the balls before the first stick, the second school gets all the balls between stick 1 and stick 2, the third school gets the balls between sticks 2 and 3 and the last school gets all remaining balls.
  The problem reduces to take 11 consecutive spots which we will use to localize the balls and the sticks and select 3 places to put the sticks. The amount of ways to do this is 
 As a result, we have 165 ways to distribute the blackboards.
If each school needs at least 1 blackboard you can give 1 blackbooard to each of them first and distribute the remaining 4 the same way we did before. This time there will be 4 balls and 3 sticks, so we have to put 3 sticks in 7 spaces (if a school takes what it is between 2 sticks that doesnt have balls between, then that school only gets the first blackboard we assigned to it previously). The amount of ways to localize the sticks is 
. Thus, there are only 35 ways to distribute the blackboards in this case.