Answer:
Neon and lithium.
Step-by-step explanation:
4x = 79.9 atomic mass
x = 19.98 atomic mass
The element having the nearest atomic mass to 19.98 is neon with an atomic mass of 20.180.
==
8y = 2*(28.085)
8y = 56.17
y = 7.021
The element having the nearest atomic mass to 7.021 is lithium with an atomic mass of 6.94..