Final answer:
The multiplication of three and seven ninths (which is 31/9) by five results in 170/9. After converting this back to a mixed number, the answer is eighteen and eight ninths, which matches option b.
Step-by-step explanation:
The question asks to multiply three and seven ninths by five. To do this, first express the mixed number as an improper fraction. Three and seven ninths is the same as 31/9 (3 x 9 + 7 = 34, therefore 34/9). Next, multiply the improper fraction by 5:
- (34/9) × 5 = 34/9 × 5/1 = 170/9
Now, convert this back into a mixed number:
- 170 divided by 9 is 18 with a remainder of 8.
- So, 170/9 is equal to eighteen and eight ninths.
Therefore, the correct answer is eighteen and eight ninths (option b).