What is the solution to the following system?

4+=3

28+4=9

520+7=19

Let s and t be dummy variables such that s and t go from 0 to positive infinity. The solution set is (4s + t + 4, s, 2t + 1, t).

Let s and t be dummy variables such that s and t go from negative to positive to infinity. The solution set is (4s + t + 4, s, 2t + 1, t).

Let s and t be dummy variables such that s and t go from 0 to 234. The solution set is (4s + t + 4, s, 2t + 1, t).

This system of linear equations has no solution.

Let s and t be dummy variables such that s and t go from negative infinity to 0. The solution set is (4s + t + 4, s, 2t + 1, t).