A) To solve the equation X - 6/4 = (7/2)^8 × (7/2)^7, we can simplify the right side of the equation first.

(7/2)^8 × (7/2)^7 = (7/2)^(8+7) = (7/2)^15

Now, we can rewrite the equation as:

X - 6/4 = (7/2)^15

To simplify further, we can convert 6/4 to 3/2:

X - 3/2 = (7/2)^15

To isolate X, we can add 3/2 to both sides of the equation:

X = (7/2)^15 + 3/2

B) To solve the equation (156 + X) - 48 = 615, we can simplify the left side of the equation first.

(156 + X) - 48 = 615

156 + X - 48 = 615

To isolate X, we can subtract 156 from both sides of the equation:

X - 48 = 615 - 156

X - 48 = 459

To isolate X, we can add 48 to both sides of the equation:

X = 459 + 48

C) To solve the equation 86 / X + 15 = 678, we can simplify the left side of the equation first.

86 / X + 15 = 678

To isolate X, we can subtract 15 from both sides of the equation:

86 / X = 678 - 15

86 / X = 663

To isolate X, we can multiply both sides of the equation by X:

86 = 663X

To isolate X, we can divide both sides of the equation by 663:

X = 86 / 663