3+$3*0.3^{5}/5$+$3*0.3^{10}/50$+$0.3^{7}/14$+$0.3^{2}/2$+
1 : n = 48 : 144
(10x-5y/48xy^2)/(4x^2-y^2/16x^3y)
4.5%*165000
48 : 96 = n : 2
6:4=9:
1175*4/100
4 : n = 12 :15
n : 3 = 12 : 18