
Regardless of the sign of

, we have

(never negative). But multiplying by -1 makes it negative.
On the other hand,

which can never be negative for real

.
Answer:
21
Step-by-step explanation:
Given that 2 parts of the ratio equals 14 green marbles, then divide to find the value of one part of the ratio.
14 ÷ 2 = 7 ← value of 1 part of the ratio, thus there are 7 blue marbles
Total marbles = 14 + 7 = 21
Subtract original amount from new amount:
84 - 39 = 45
He bought 45 books.
The answer is option 2,
2x10^10