Question 57310
0.4x+1x = 0.5
x+y = 20
	
0.4x+1y = 0.5	0.6y = -7.5			y = -12.5
0.4x+0.4y = 8	0.6y/0.6 = -7.5/0.6

Sub In

0.4x+1(-12.5) = 0.5
0.4x(+-)12.5 = 0.5
0.4x-12.5(+12.5) = 0.5(+12.5)
0.4x = 13
0.4x/0.4 = 13/0.4
x = 32.5

Proof - Sub In Again

0.4(32.5)+1(-12.5) = 0.5
13+-12.5 = 0.5
0.5 = 0.5

N.P.
J-Man