Answer:
3cm per day
54cm long
Step-by-step explanation
Let x be yesenia's unit rate
If yesenia knits 21 centimeters of a scarf every week, then;
21 cm = 1 week (7 days)
To determine the amount for her knitting in a day, we can write;
x = 1 day
Divide both expressions
21/x = 7/1
Cross multiply
7 * x = 21
7x = 21
x = 21/7
x = 3
hence yesenia's unit rate is 3cm per day
- Recall that;
21 cm = 1 week (7 days)
Let y be the length of the scaf sfter 18 days, To get the length of the scarf, we can write;
y = 18days
Divide both resulting expressions;
21/y = 7/18
7y = 21 * 18
y = 3 * 18
y = 54cm
Hence the scarf will be 54cm longy