Where is your question?! please dont post pictures.
Your question is very unclear: how many years have past/months? If it's just how kuch it's depeeciated in one year the the answer would be 28,000•.25=7000 thus in one year the car is worth 7000$ less each year
The value of x is
and 
Step-by-step explanation:
The equation is 
Subtracting by
on both sides,

Taking LCM,

Multiplying by 3x on both sides,

Dividing by (-) on both sides,

Using quadratic formula, we can solve for x.

Taking out common term 2, we get,

Thus, the value of x is
and 
Simple interest = Cost Price + (Interest Percentage of Cost Price × number of years or months we are paying off)
a) SI = £20 000 + (5% of £20 000 × 4)
SI = £20 000 + (£1000 × 4)
SI = £20 000 + £4000 = £24 000
b) SI = £20 000 + (5% of £20 000 × 3)
SI = £20 000 + (£1000 × 3)
SI = £20 000 + £3000 = £23 000
£24 000 - £23 000 = £1000 that you saved!