I think the rule might be x-9
So, you know that any number with 100 as the denominator will be a fraction. All you have to do is change the 10 you have now to 100. To do that, you have to multiply BOTH numerator and denominator (top and bottom) by 10. That results in 70/100, which is equal to 70%.
The equivalent percent for 7/10 is 70%.
Not 100% sure if this is how you do it but I tried.
Answers:
10mi
approx. 42.98ft.
60yd
approx. 73.31ft.
approx. 0.90ft.
approx. 12.37ft.
19.18/2.8= 6.85 hours or rounded it would be 7 hours