Answer's for today's questions.

First there are 4 steps .
First step: Isolate the variable
Second step: Reverse the operations
Third step: It become's a zero pair, and then the variable is isolated by itslef so you solve the question.
Fourth step: Rewrite the question and check your answer.

First Question: A+4=10
A+4-4=10-4
10-4=6
Check it :
10+4= 10
6+4=10
10=10 .
A= 6.

Second Question:
B-2=5
B-2+2=5+2
B=7
Check it.
B-2=5
7-2=5
5=5
B=7

Third Question: / = Divided
W/3=6 ( divided)
Wx3=6x3
6x3=15
Check it.
W/3=6
18/3=6
6=6
W= 18.

Fourth Question: / = Divided , brackets means multiplying.
3C=21
3/3=21/3=7
Check it.
3C=21
3(7)=21
21=21
C=7

Fifth Question: / = Divided
F/3-2=1
F/3+2+1+2
Check it.
F/3-2=1
1+2=3
9/3-2=1
3-2=1
1=1
F= 9.

Sixth Question: / = Divided. brackets means multiply.
2J+1=9
2J=1-1+9-1.
2/2=8/2
Check it.
2J+1=9
2(4)+1=9
8+1=9
9=9
J=4.