18x - 16y = - 312

78x - 16y = 408

(-12,6)

Step-by-step explanation:

using elimination method multiply the second equation by - 1

18x - 16y = - 312

-78x + 16y = - 408

add the two equations

60x = - 720

divide by 60

x = - 12

plug - 12 into the first equation

18 (-12) - 16y = - 312

-216 - 16y = - 312

-16y = - 96

y = 6