I don't think that there is a number that can add to 13 exactly, because 12 times 2 is 24 and it equals 14. 3 and 8 equals 11, and 24 and 1 equals 24.
Answer is F-1(x)= x/5-2 it is x over 5 minus 2
1 - 5/15 + 3/15
Just use common denominators!
Hope that helped. :)
400 miles -----------4 hours
X miles ------------2 hours
4x=400.2
4x=800
X=200
Or
400miles --------------- 4hours
X miles --------------- 6 hours
4x=400.6
4x=2.400
X= 600
A really easy way to do this would be converting them all to decimals by dividing the top number by the bottom number.
7/5 = 1.4
15/4 = 3.75
3/2 = 1.5
11/4 = 2.75
13/3 = 4.33
Start with the whole numbers. 3/2 and 7/5 must go first since they both have a 1. 7/5 goes before 3/2 since it has a 4 in the tenths place, while 3/2 has a 5.
Next would be 11/4 since it has a 2, then 15/4 with a 3, and lastly 13/3 with a 4 as a whole number
Answer is 7/5 , 3/2 , 11/4, 15/4 , 13/3