5) k/35=3/7 : cross multiply
35*3=7k : simplify
105=7k : divide both sides of the equation by 7
k=15
6) 3/t=18/24 :cross multiply
18t=24*3 :simplify
18t=72 : divide both sides of the equation by 18
t=4
7) 10/8.4 = 5/m :cross multiply
10m=5 * 8.4 :simplify
10m=42 :divide both sides by 10
m=4.2