Explanation

subtract 4 from both sides:

a/2 + 4 - 4 = 7/2 - 4

a/2 = 7/2 - 8/2

 Simplify the right side of the equation by subtracting the fractions:

a/2 = (7 - 8)/2

a/2 = -1/2

Multiply both sides of the equation by 2 to eliminate the fraction:

2 * (a/2) = 2 * (-1/2)

a = -1