You need to use the following notations for computers and hard drives, such that:

x represents the number of computers

y represents the number of hard drives

Since the problem provides the information that the computer store sold a total of 36 computers and external hard drives , in one week, ...

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You need to use the following notations for computers and hard drives, such that:

x represents the number of computers

y represents the number of hard drives

Since the problem provides the information that the computer store sold a total of 36 computers and external hard drives , in one week, you can put the statement into the following mathematical equation, such that:

`x + y = 36 => x = 36 - y`

Since the problem provides the information that computers were sold for `$1180` per unit and hard drives for `$125` per unit and the revenue from these sales was `$22,435` , yields:

`1180x + 125y = 22,435`

You need to replace `36 - y` for` x` in the equation `1180x + 125y = 22,435` , such that:

`1180(36 - y) + 125y = 22,435`

`42,480 - 1180y + 125y = 22,435`

`1055y = 42,480 - 22,435 => 1055y = 20045 => y = 19`

`x = 36 - 19 => x = 17`

**Hence, evaluating how many computer and hard drives the store sold, yields x = 17 (computers) and y = 19(hard drives).**