50w=5%p=2.5w
55w=5%*50w+5w*10%=2.5+0.5=3w =5.455%
60w=5%*50w+10w*10%=2.5+1=3.5w
65w=5%*50w+15w*10%=2.5+1.5=4w
70w=5%*50w+20w*10%=2.5+2=4.5w
75w=5%*50w+25w*10%=2.5+2.5=5w
80w=5%*50w+30w*10%=2.5+3=5.5w
85w=5%*50w+35w*10%=2.5+3.5=6w
90w=5%*50w+40w*10%=2.5+4=6.5w =7.222%
95w=5%*50w+45w*10%=2.5+4.5=7w =7.368%
99.999999w=2.5+5=7.5w;;;;;; =7.5%