Since you didn't provide expression to see which one is equivalent,, I will simply solve the expression you provided. If you need help finding out which expression option is equivalent after I solve this for you,, let me know and I would be more than happy to help you figure it out.
The first step for solving this expression is to calculate the difference between 20 and 21. We can start solving this by keeping the sign of the number with the larger absolute value and subtract the smaller absolute value from it. This will look like the following:
-(21 - 20)
Now subtract the numbers and add it back into the expression.
-1 + 8y - 9y
Next we need to collect the like terms with a y variable by subtracting their coefficients.
(8 - 9)y
Calculate the difference in the parenthesis.
-1y
Remember that when the term has a coefficient of -1,, the number doesn't have to be written but the sign must remain.
-y
Lastly,, add this back into the expression to get your final answer.
-1 - y
Let me know if you have any further questions.
:)
Answer:
165
Step-by-step explanation:
55*3= 165
Hope this helps!
Answer:
B
Step-by-step explanation:
because the angles 1 and 7 are alternate and equal , we can conclude that p and q are parralel
Use the conditional probability formula, P(a|b) = P(a and b)/P(b)
Answer:
a) 
b) 
Step-by-step explanation:
By definition, we have that the change rate of salt in the tank is
, where
is the rate of salt entering and
is the rate of salt going outside.
Then we have,
, and

So we obtain.
, then
, and using the integrating factor
, therefore
, we get
, after integrating both sides
, therefore
, to find
we know that the tank initially contains a salt concentration of 10 g/L, that means the initial conditions
, so 

Finally we can write an expression for the amount of salt in the tank at any time t, it is 
b) The tank will overflow due Rin>Rout, at a rate of
, due we have 500 L to overflow
, so we can evualuate the expression of a)
, is the salt concentration when the tank overflows