Four milkmen rented a pasture. A grazed 15 cows for 4 months, B grazed 12 cows for 2 months, C grazed 18 cows for 6 months and D grazed 16 cows for 5 months. If A's share of rent is Rs. 1020, what is C's share of rent ?

$$\eqalign{ & = {\text{A}}:{\text{B}}:{\text{C}}:{\text{D}} \cr & = 15 \times 4:12 \times 2:18 \times 6:16 \times 5 \cr & = 60:24:108:80 \cr & = 15:6:27:20 \cr & {\text{Let the total rent be Rs}}{\text{.}}x \cr & {\text{Then,}} \cr & {\text{A's share}} = {\text{Rs}}{\text{.}}\left( {\frac{{15x}}{{68}}} \right) \cr & \therefore \,\frac{{15x}}{{68}} = 1020 \cr & \Rightarrow x = \left( {\frac{{1020 \times 68}}{{15}}} \right) \cr & \Rightarrow x = 4624 \cr & {\text{Hence, C's share}} \cr & = {\text{Rs}}{\text{.}}\left( {4624 \times \frac{{27}}{{68}}} \right) \cr & = {\text{Rs}}{\text{.}}\,{\text{1836}} \cr} $$