Commission earned by William is $ 45.84
<h3><u>
Solution:</u></h3>
Given that,
William makes a commission of 6% percent on everything he sells
He sells a computer for $764.00
<em><u>To find: Commission amount of William</u></em>
Given that he makes a commission of 6 % on everything he sells. So he has received a commission of 6 % of $ 764.00
Commission amount of William = 6 % of $ 764.00
a % of b can be written in fraction as 

Thus commission earned by William is $ 45.84
Answer:
Recall that a relation is an <em>equivalence relation</em> if and only if is symmetric, reflexive and transitive. In order to simplify the notation we will use A↔B when A is in relation with B.
<em>Reflexive: </em>We need to prove that A↔A. Let us write J for the identity matrix and recall that J is invertible. Notice that
. Thus, A↔A.
<em>Symmetric</em>: We need to prove that A↔B implies B↔A. As A↔B there exists an invertible matrix P such that
. In this equality we can perform a right multiplication by
and obtain
. Then, in the obtained equality we perform a left multiplication by P and get
. If we write
and
we have
. Thus, B↔A.
<em>Transitive</em>: We need to prove that A↔B and B↔C implies A↔C. From the fact A↔B we have
and from B↔C we have
. Now, if we substitute the last equality into the first one we get
.
Recall that if P and Q are invertible, then QP is invertible and
. So, if we denote R=QP we obtained that
. Hence, A↔C.
Therefore, the relation is an <em>equivalence relation</em>.
You can use the sum and difference identities which for cosine is cos(a+b)= cosacosb-sinasinb
A system of equations is good for a problem like this.
Let x be the number of student tickets sold
Let y be the number of adult tickets sold
x + y = 200
2x + 3y = 490
x = 200 - y
2(200 - y) + 3y = 490
400 - 2y + 3y = 490
400 + y = 490
y = 90
The number of adult tickets sold was 90.
x + 90 = 200 --> x = 110
2x + 3(90) = 490 --> 2x + 270 = 490 --> 2x = 220 --> x = 110
The number student tickets sold was 110.