Calculating deposit based on interest and required withdrawal in future

Question

I am really stuck with example 2-5 and 2-6. I don't really understand example 2-6 and example 2-5 I just can't figure out...I was able to do example 2-4 which was easy...

For example 2-4 I did F=P(1+ interest)^n

6500=P(1+0.03)^4

I solved for P and got the deposit value...Example 2-5 or 2-6 are different and don't work the same way so I am not sure what to do here..

Answer 1

For example 2-5: you want

$$ 6500 + Q = P (1.03)^4$$

and

$$3000 = Q (1.03)$$

so that

$$ = 6500 + \frac{3000}{1.03} = P (1.03)^4$$

Solve for $P$.

Answer 2

2-5: $\frac{6500}{1.03^4} + \frac{3000}{1.03^5}$

2-6: $900,000 + 200,000[\frac{1}{1.04} + \frac{1}{1.04^2} + \frac{1}{1.04^3} + \frac{1}{1.04^4} + \frac{1}{1.04^5}]$ assuming costs due at end of each year and interest paid annually

2-7: $500,000 + 300,000[\frac{1}{1.04} + \frac{1}{1.04^2} + \frac{1}{1.04^3} + \frac{1}{1.04^4} + \frac{1}{1.04^5}]$

These arent good questions