Question 241679
multiply 1st eqn by -3 and add to 2nd eqn ___ -5/b + 7/c = -28 (I)


multiply 1st eqn by -2 and add to 3rd eqn ___ -3/b + 7/c = -11 (II)


subtract eqn (I) from (II) ___ 2/b = 17 ___ 2/17 = b


substituting ___ -3/(2/17) + 7/c = -11


-51/2 + 7/c = -11 ___ 7/c = 29/2 ___ c = 14/29


substituting ___ 1/a + 1/(2/17) - 2/(14/29) = 9 ___ 1/a + 17/2 - 58/14 = 9


1/a + 119/14 - 58/14 = 126/14 ___ 1/a = 65/14


a = 14/65