Final answer:
The equation d-21.4=87.9 is solved by adding 21.4 to both sides, resulting in d = 109.3.
Step-by-step explanation:
The question posed is d-21.4=87.9. To solve for d, we need to isolate the variable by performing the inverse operation on both sides of the equation. Since 21.4 is subtracted from d, we need to add 21.4 to each side to cancel it out on the left side.
Step-by-step:
- Add 21.4 to both sides of the equation: d - 21.4 + 21.4 = 87.9 + 21.4.
- This simplifies to: d = 109.3.
Thus, the value of d is 109.3.