The easiest way to do this is the following: if the amount increases with 7% each year, it means that you have to multiply the £400 by 1,07. Then you multiply that answer by 1,07 and one time again. The final answer is 490,0172
AD=9 units. AB=3 units. thus: 9/3=3
So to find the answer you would use the formally 1/2bh
1/2(3.5)(1.5)
which give you 2.625
