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Equation A: 2x + 5y = 8

Equation B: 4x + y = 7

2A: 4x + 10y = 16

2A - B: 9y = 9, Therefore y = 1

Sub y back into equation A to find x:  2x + 5 = 8,  2x ...

times both sides by both denominators

= (2x+3)(2x+1) - (2x-8)(x-4) = (2x+1)(x-4)

times out brackets

= (4x² + 8x +3) - (2x² -16x +32) = 2x² -7x -4

The first thing you need to do is collect all the 'like terms' on the same side of the equation. Start with the 'x' terms and remember to reverse the signs as you cross them over to the other side. 

1. Move everything to the same side: 2x^3-12X^2-10x=0 2.Take out a factor of 2x: 2x(x^2-6x-5)=0 3.Complete the square on the quadratic: 2x[(x-3)^2-14]=0

x ≤ -4.5