The ratio of sports cars to the total number of cars on display in Ken's car shop was 3 : 10. ⁴₇ of the remaining cars on display were electric cars and the rest were saloon cars and family cars in the ratio of 3 : 1. If there were 60 more sports cars than saloon cars, how many family cars were there?

Sports Cars	Electric Cars	Saloon Cars	Family Cars	Total Cars
3x4	7x4			10x4
	4x4	3x4		7x4
		3x3	1x3
12 u	16 u	9 u	3 u

The total number of saloon cars and family cars is the combined repeated identity. Make the total number of saloon cars and family cars the same. LCM of 3 and 4 is 12.

The total number of electric cars, saloon cars and family cars is the next combined repeated identity. Make the total number of electric cars, saloon cars and family cars the same. LCM of 7 and 7 is 28. 

Number of more sports cars than saloon cars
= 12 u - 9 u
= 3 u

3 u = 60

1 u = 60 ÷ 3 = 20

Number of family cars
= 3 u
= 3 x 20
= 60

Answer(s): 60