Harga 4 1/2 liter bensin Rp 20.250. Harga 3 liter bensin adalah

[tex] 4\frac{1}{2} [/tex] liter bensin = Rp 20.250,-
1 liter bensin = Rp 20.250,- ÷ [tex]4\frac{1}{2}[/tex] = Rp 4.500,-

Harga 3 liter bensin = 3 × Rp 4.500,- = Rp 13.500,-

misal harga 1 liter bensin = x

maka
4 1/2 x = 20.250
9x/2 = 20.250
x = 2/9 x 20.250
x = Rp. 4.500

harga 3 liter bensin
3x = 3 x Rp. 4.500
     = Rp. 13.500