Verified Answer :

Scryt

One thing before we start :)

AS you can see both numbers after equation have to be negative, 
also we know that 2 same numbers have to add up to -12 and those 2 number after multiplication have to be equal -28

Some theory:

We know that any number which is not negative multiplied by negative will result in negative result, to make it more clear 

\((+)*(-)=(-)\)

but

\((-)*(-)=(+)\)

we have 2 unknown numbers, let's say it's \(x\) and \(y\)

\(x+y=-12\)
\(x*y=-28\)

for \(x=2\)
for \(y=-14\)

\(2+(-14)=2-14=-12\)
\((2)*(-14)=-28\)

So your answer is 2 and -14 ;)