Solve the following simultaneous equations using an appropriate method.
a) 2x + y = 8
4x + 3y = 16
b) -3x + 2y = 19
4x + 5y = 13
c) -3x + 7y = 9
4x - 3y = 7
d) -4x + 5y = -7
x = 23 - 3y

A) SUBSTITUTION: 4x + 3(-2x +8)=16
4x + -6x + 24 = 16
-2x= -8
x= 4
y= 0

b) ELIMINATION:
12x -8y = -76
-12x -15y = -39
-23y= -115
y=5
x= -3

c) ELIMINATION:
-12x+28y=36
12x-9y=21
19y= 57
X=4
y=3

d) SUBSTITUTION:
-4(23 -3y) +5y=-7
-92+12y+5y =-7
-92 +17y = -7
17y = 85
y=5
x=8

The answer is biodiversity resulting from new ancestors.