Explanation:
To solve the equation -16(d + 1) = -21 for d, we can first use the distributive property to expand the expression -16(d + 1):
-16(d + 1) = -16d - 16
Then, we can set the two sides of the equation equal to each other and solve for d:
-16d - 16 = -21
-16d = -5
d = 5/16
Therefore, the value of d that satisfies the equation -16(d + 1) = -21 is d = 5/16.