To answer this we want to split up the 'a' parts and 'b' parts of the question and answer them seperately because we can't answer the question with two letters. We can change one equation to b=16-6a and now substitute this equation for b into the other equation: 5a - 2(16-6a)=19. Now multiply out the bracket: 5a - 32 +12a=19. Now we can solve this equation for a: 17a=51 which means that a=3. Now we know what a is we can put this into the equation that tells us b: b=16-6(3)--> b=-2. And now we have our two answers a=3 and b=-2. You can check this is right by putting both number back into the original equations and checking that the equations work.