A graph shows the solutions to be
(x, y) = (-6, 312) or (6, 312)
To solve algebraically, remove a factor of 2 from the second equation and use that expression to substitute for y in the first equation.
10x^2 -(8x^2 +24) = 48
2x^2 = 72
x = ±√(72/2) = ±6
y = 8*36 +24 = 312