I hope this help you with what you need
1. 3y
multiplying 3 and y together gets 3y
2. y-5
5 less implies that we subtract 5 from y
3. y+7
adding 7 to y, self-explanatory
4. 9y
same thing as #1
5. 
quotient of implies division, since number y is listed first, y is the numerator
4023/x=100/75
(4023/x)*x=(100/75)*x
4023=1.3333333333333*x
x=4023/1.3333333333333
x=3017.25
64,000/2=32,000
32,000/12= $2,666.67 per paycheck