Final Answer:
a.

b.

c.

Step-by-step explanation:
For equation a,
adding 10 to both sides gives
Dividing by 9, we have
. Solving for
or
results in
or
but only
is valid.
For equation b,
subtracting 4 yields
Dividing by 3 gives
. Solving for
or
gives x = 7 or x = -9, but only x = 4 satisfies the original equation.
Lastly, for equation c,
, subtracting 7 gives
Dividing by 4 results in
Solving for
or
gives x = 24 or x = -6, but only x = 15 satisfies the original equation. In conclusion, the correct solutions for the given equations are
for a, x = 4 for b, and x = 15 for c.