1 yd ----------------------- 3 ft
1 mi ----------------------- 5280 ft
number of yards = ? 4 mi
Then
1 mi ----------------------- 5280 ft
? mi ---------------------- 3 ft
x = (3 x 1) / 5280
x = 5.68 x 10^-4 mi
5.68 x 10^-4 mi --------------------- 1 yd
4 mi --------------------- ?
x = (4 x 1) / 5.68 x 10^-4
x = 7040 yd
