Problem:
Solve the following system of two equations: 
$-21 x+4 y-23=0$, $15 x+4=0$
Answer:
$x=-\frac{4}{15}$, $y=\frac{87}{20}$
{'source': 'AMPS', 'file': 'amps/mathematica/algebra/system_of_equations/24125.txt'}