A farmer finds that he can buy 5 sheep and 5 cows for $129or 10 sheep and 17 cows for $177. how much will it cost him to buy 3 sheep and 2 cows

Let the cost of one sheep and one cow be x and y respectively.

Therefore,

5x+5y=129

10x+17y = 177

Solving the two equations,

Multiply the first equation by 2 and subtract the second from the results;

10x+10y = 258

10x+17y = 177

0x-7y = 81 = > y = $-11.57 (cannot be a negative value). The details of the question need to be checked.

Now,

5x+5y = 129 = > 5x-57.86 = 129=>5x = 186.86 = > x = $37.37