Im doin a paper and stuck on this one, im not very good at these :P
I will rep the answerer!!
In the first month after opening, a mobile phone shop sold 280 phones. A model for future trading assumes that sales will increase by x phones per month for the next 35 months, so that (280 + x) phones will be sold in the second month, (280 + 2x) in the third month, and so on.
Using this model with x = 5, calculate
(a) (i) the number of phones sold in the 36th month,
(ii) the total number of phones sold over the 36 months.
The shop sets a sales target of 17 000 phones to be sold over the 36 months.
Using the same model,
(b) find the least value of x required to achieve this target.