Answer :
Solve for B by simplifying both sides of the equation, then isolating the variable. So in this case B=A....
A = 1/2 (A + B)
distribute the 1/2 into the parentheses
A = 1/2A + 1/2B
Subtract 1/2A from each side
A - 1/2A = 1/2B
Combine like terms
1/2A = 1/2B
Isolate B by dividing each side by 1/2
1/2A ×2/1 = B
Multiply
2/2A = B
A = B
distribute the 1/2 into the parentheses
A = 1/2A + 1/2B
Subtract 1/2A from each side
A - 1/2A = 1/2B
Combine like terms
1/2A = 1/2B
Isolate B by dividing each side by 1/2
1/2A ×2/1 = B
Multiply
2/2A = B
A = B