To determine which student correctly describes how to use the count-up method to find [tex]\(10 - 7.49\)[/tex], let's examine each student's steps in detail one by one:
### Ari
1. Add 9 hundredths to 7.49:
[tex]\[ 7.49 + 0.09 = 7.58 \][/tex]
2. Add 4 tenths to 7.58:
[tex]\[ 7.58 + 0.4 = 7.98 \][/tex]
The final sum is 7.98, which is not 10. So, Ari is incorrect.
### Nora
1. Add 1 hundredth to 7.49:
[tex]\[ 7.49 + 0.01 = 7.50 \][/tex]
2. Add 6 tenths to 7.50:
[tex]\[ 7.50 + 0.6 = 8.10 \][/tex]
3. Add 2 (two ones) to 8.10:
[tex]\[ 8.10 + 2 = 10.10 \][/tex]
The difference she stated is 2.49, but we reached 10.10, not 10. Thus, Nora is incorrect.
### Shama
1. Add 5 hundredths to 7.49:
[tex]\[ 7.49 + 0.05 = 7.54 \][/tex]
2. Add 1 tenth to 7.54:
[tex]\[ 7.54 + 0.1 = 7.64 \][/tex]
3. Add 2 (two ones) to 7.64:
[tex]\[ 7.64 + 2 = 9.64 \][/tex]
The final sum is 9.64, not 10, so Shama is incorrect.
### Yoko
1. Add 1 hundredth to 7.49:
[tex]\[ 7.49 + 0.01 = 7.50 \][/tex]
2. Add 5 tenths to 7.50:
[tex]\[ 7.50 + 0.5 = 8.00 \][/tex]
3. Add 2 (two ones) to 8.00:
[tex]\[ 8.00 + 2 = 10.00 \][/tex]
Yoko correctly arrives at 10. Therefore, Yoko's method is correct.
So, the correct student who describes how to use the count-up method to add from 7.49 to find [tex]\(10 - 7.49\)[/tex] correctly is Yoko.
Therefore, the correct answer is:
[tex]\[ \boxed{Yoko} \][/tex]
