Showing your working clearly, solve the following simultaneous equations:

y+5x=3
2x^2-1=3xy+y^2

Use substitution. y = 3 - 5x

2x^2 -1 = 9x -15x^2 +9 -30x +25x^2
Combine terms to form a quadratic in x.
8x^2 -21x +10 = 0
That can be factored with rational constants, since b^2-4ac = 11.
x = (1/16)*[21 +/- sqrt121)
= (1/16)[10 or 32]
= 2 or 5/8
(2x-4)(4x -2.5) = 0 is the factored form

y = 3 - 5*2 = -7 if x = 2
y = 3 - 25/8 = -1/8 if x = 5/8