Question 751548
Multiply the second equation by 3, the result is:

{{{12s-9t=45}}}

Now line up this equation and the first equation and add them up by adding like terms, the result will be:

{{{17s=51}}}

Divide both sides by 17:

{{{s=3}}}

Now plug in 3 for s, in any equation used in the problem.  I'll use the first equation:

{{{5s+9t=6}}}

{{{5(3)+9t=6}}}

{{{15+9t=6}}}

Subtract 15:

{{{9t=-9}}}

Divide by 9:

{{{t= -1}}}