Answer:
Number of Spiders: 8
Number of Dragonflies: 7
Number of Houseflies: 5
Step-by-step explanation:
s= spider
d= dragonfly
h= housefly
Heads:
20= s+d+h
Legs:
136= 8s+6d+6h
Wings:
19= 0s+2d+1h
Solve with substitution.
Divide the second equation by 2.
136= 8s+6d+6h
68= 3d+3h+4s
Set the last equation in terms of d.
19= 0s+2d+1h
d= [tex]\frac{19}{2} -\frac{1}{2}h[/tex]
Substitute what we just found (d) into the first and our new second equation. Simplify.
20= s+d+h
20= s+[tex]\frac{19}{2} -\frac{1}{2}h[/tex]+h
h+2s=21
68= 3d+3h+4s
68= 3([tex]\frac{19}{2} -\frac{1}{2}h[/tex])+3h+4s
3h+8s=79
Take both simplified equations and solve with elimination. Do this by multiplying the top equation by negative 3.
h+2s=21
3h+8s=79
-3h-6s=-63
3h+8s=79
2s=16
s=8
Plug in s=8 into the other equation.
h+2s=21
h+2(8)=21
h=5
Plug in h=5 into the last equation we rewritten.
[tex]d= \frac{19}{2} -\frac{1}{2} h[/tex]
[tex]d=\frac{19}{2} -\frac{1}{2}(5)[/tex]
d=7
(d,h,s)= (7,5,8)
