대답:
# x = -8 / 3 #
# y = 17 / 6 #
설명:
# 5x + 4y = -2 #
# x-4y = -14 #
첫 번째 방정식을 두 번째 방정식에 더함으로써
# 5x + 4y + x-4y = -2-14 #
# x-4y = -14 #
# 6x = -16 #
# x-4y = -14 #
# x = -16 / 6 #
# x-4y = -14 #
# x = -8 / 3 #
# -8 / 3-4y = -14 #
# x = -8 / 3 #
# 4y = -8 / 3 + 42 / 3 #
# x = -8 / 3 #
# 4y = 34 / 3 #
# x = -8 / 3 #
# y = 34 / 12 #
# x = -8 / 3 #
# y = 17 / 6 #