Soooooo sorry but I only understood part a and c.
sorry
 
        
                    
             
        
        
        
No
645 becomes 650 when rounded to the nearest ten
645 becomes 600 when rounded to the nearest hundred
        
             
        
        
        
Answer:
Step-by-step explanation:
try https://www.mathpapa.com/calc.html?q=y%3D2x+1 for faster answers next time
 
        
             
        
        
        
Answer:
D.
Step-by-step explanation:
1. Answer A:
15 students signed up for violin lessons (4 boys + 11 girls)
15 / 70 = approx. 21% of the class.
Answer A says 28%, so this is incorrect.
2. Answer B:
17 students signed up for drum lessons (11 boys + 6 girls)
17/70 = approx. 24%
B says 17% signed up for drums, so this is incorrect.
3. Answer C.
Wrong because more girls signed up for piano lessons (15 girls, whereas only 9 boys signed up for piano)
4. D. The same percent of boys and girls are taking guitar lessons.
Get the total number of boys and girls in the class (just add the results for each separately for all instruments)
Boys: 11 + 6 + 9 + 4 = 30
Girls: 6+8+15+11 = 40
6 out of 30 boys signed up for guitar
6/30= 20%
8 out of 40 girls signed up for guitar
8/40 = 20%
Answer is D