Question 1185383
**a.** Let 'C' be the total cost and 'x' be the area in cm². The expression for the total cost is:

C = 9000 + 50x

**b.** The advertising budget is between £10,800 and £12,500. So, the inequality is:

10800 ≤ C ≤ 12500

Substitute the expression for C:

10800 ≤ 9000 + 50x ≤ 12500

Subtract 9000 from all parts of the inequality:

10800 - 9000 ≤ 50x ≤ 12500 - 9000
1800 ≤ 50x ≤ 3500

Divide all parts by 50:

1800/50 ≤ x ≤ 3500/50
36 ≤ x ≤ 70

Therefore, the minimum area that could be used is 36 cm², and the maximum area is 70 cm².