The monthly interest rate is 6%/12 = 0.5%. The interest earned each month is
0.005*$500,000 = $2500
You can withdraw $2500 each month without disturbing the principal amount.
5x = 20...where x = number of months
x = 20/5
x = 4...it would take Tom 4 months to save $20
2z +7 = -5
2z = -5 -7
2z = -12
z= -12 /2
z= -6
Let's call that number x, twice the number will be 2x, sum of it and 5 is, 2x+5. So if this expression is at most 15, it means, it can be only less than 15 and equal to 15. Let's show this as an inequality.

Let's solve.

![x\quad \in \quad \left[ -\infty ,5 \right]](https://tex.z-dn.net/?f=x%5Cquad%20%5Cin%20%5Cquad%20%5Cleft%5B%20-%5Cinfty%20%2C5%20%5Cright%5D%20)
If the number is a natural number. The values it can take is,