Not sure what the extra numbers and equation are, but I'll just solve it.*Note* first number and second number isn't really assigned, just shows one of the numbers of the two*
F= first number
S= second number
F+S=78
F-S= 32
Now, you want to eliminate F, so you'll multiply the first equation by -1
-(F+S=78)
F-S=32
-F-S=-78
F-S=32
-2S=-46
S=23
Now plug in the number to one of the equations.
F+23=78
78-23= 55
The two numbers are 55 and 23.