B
calculate the slopes m of the 2 lines using the gradient formula
m = (y₂ - y₁ ) / (x₂ - x₁ )
with (x₁, y₁ ) = C(- 2, 4) and (x₂, y₂ ) = D(0, - 4 )
=
=
= - 4
repeat with (x₁, y₁ ) = F(- 4, 0 ) and (x₂, y₂ ) = G(4, 2 )
=
=
=
The 2 lines are perpendicular because their slopes are negative reciprocals
According to the ratio of dogs to cats, if there are 20 cats, there will be 35 dogs.
<u>Explanation:</u>
Let the number of dogs be d and the number of cats be c
If the ratio of dogs to cats is 49:28, then the ratio of d : c would be
On reducing the fraction, we get
It is shown that the number of cats is reduced to 20.
So, let the number of dogs after sometime be x
Thus,
After cross multiplying we get:
140 = 4x
x = 35
According to the ratio of dogs to cats, if there are 20 cats, there will be 35 dogs.