Answer:

Explanation:
What is being done will be written in brackets on the right
w = 3(2a+b)-4
w + 4 = 3(2a+b) [4 is added on both sides of the equation]
w + 4 = 6a + 3b [the brackets on the right is expanded]
w + 4 - 3b = 6a [3b is subtracted on both sides of the equation]
w/6 + 4/6 - 3b/6 = a [both sides are divided by 6]
a = w/6 +2/3 - b/2