Y = 3x - 7...slope here is 3 and y int is -7
3x + 9y = 9
9y = -3x + 9
y = -1/3x + 1....slope here is -1/3 and y int is 1
the slopes 3 and -1/3 are negative reciprocals of each other...therefore, ur lines are perpendicular
96÷2=48
63-48=15
So Sam should give Peter 15 of his stamps so that Peter will have twice as many stamps as him.
Answer:
Option (a) is correct.
The system of equation becomes

Step-by-step explanation:
Given : Equation 
We have to construct a system of equations that can be used to find the roots of the equation 
Consider the given equation 
To construct a system of equation put both sides of the given equation equal to a same variable.
Let the variable be "y", Then the equation 
becomes,
Thus, The system of equation becomes

Option (a) is correct.
Answer:
Jean is 9 and Tom is 15.
Step-by-step explanation:
3 years ago, Tom was 12 and Jean was 6, hence Tom was twice as old as Jean.
Since that was their age 3 years ago, they are currently 15 (Tom) and 9 (Jean).
Add 2 years to each of these ages, you get 17 and 11.
17 + 11 = 28
Write the left side of the given expression as N/D, where
N = sinA - sin3A + sin5A - sin7A
D = cosA - cos3A - cos5A + cos7A
Therefore we want to show that N/D = cot2A.
We shall use these identities:
sin x - sin y = 2cos((x+y)/2)*sin((x-y)/2)
cos x - cos y = -2sin((x+y)/2)*sin((x-y)2)
N = -(sin7A - sinA) + sin5A - sin3A
= -2cos4A*sin3A + 2cos4A*sinA
= 2cos4A(sinA - sin3A)
= 2cos4A*2cos(2A)sin(-A)
= -4cos4A*cos2A*sinA
D = cos7A + cosA - (cos5A + cos3A)
= 2cos4A*cos3A - 2cos4A*cosA
= 2cos4A(cos3A - cosA)
= 2cos4A*(-2)sin2A*sinA
= -4cos4A*sin2A*sinA
Therefore
N/D = [-4cos4A*cos2A*sinA]/[-4cos4A*sin2A*sinA]
= cos2A/sin2A
= cot2A
This verifies the identity.