The city will use 4 street lights along the city street.
To calculate the number of street lights that the city will use, we need to find the distance between each street light. The total length of the street is 7/8 mile, and the distance from the first street light to one end of the street is 3/8 mile. So, the remaining distance is 7/8 - 3/8 = 4/8 mile. Since the street lights are placed at equal intervals, we can divide the remaining distance by the interval to find the number of intervals, which is the number of street lights. The interval between the street lights is the same as the distance between them, so we have 4/8 mile divided by the interval. This can also be written as a fraction: (4/8)/(x/8), where x is the unknown number of intervals. We can simplify this fraction to 4/x. Since the fraction must be equal to 1 in order for the distance to be covered completely, we can set it equal to 1: 4/x = 1. We can cross-multiply and solve for x: 4 = x. Therefore, the city will use 4 street lights.
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