Answer:
both of the questions are examples of convenience samples
Step-by-step explanation:
A voluntary response would be where the people get to choose to respond to the survey. In both of these cases, teachers are specifically asking for their students opinions.
20,000 x 25 = 500,000
500,000 divided by 100 = 5,000 members are lost.
Members left = 15,000
Members added = 10,000
Members every year = Members left + Members added
= 15,000 + 10,000
= 25,000
I am unsure about the very last problem but I can help with the first two
1) (y+1)+4
If we combine the numbers 1 and 4, we get +5 and can isolate the numbers from the variable.
This would give us

2) (6*r)*7
remember that we do not have to explicitly state 6*r
Instead, we can write it as 6r
this helps us get rid of the parentheses
now we can write it as

I hope this helps!:)
Yes it is correct because you would multiply 30 by 7 which equals 210 + the extra 20 dollars / 50 dollars (idk).. she will have more than enough though