Answer:
a) 35, b) 25, c) 60
Step-by-step explanation:
The number of girls is 10 more than the number of boys, so it's a good thing to choose a variable to represent the number of boys.
Number of boys: b
Number of girls: b + 10
Ratio of girls:boys is 7:5, so

"Cross multiply" to get

There are 25 boys. There are 10 more girls, so the number of girls is 35, and the total number of students is 60.
That's a packed classroom!
Answer:
The required expression is
.
The value of the expression when y=20 is 2.
Step-by-step explanation:
Consider the provided phase.
3 less than the quotient of a number y and 4
The quotient of a number y and 4 can be written as: 
Now 3 less than the quotient of a number y and 4 can be written as:

Hence, the required expression is
.
Now evaluate when y=20.
Substitute y=20 in above expression.



Hence, the value of the expression when y=20 is 2.