<span>lets assume number of iphones sold = a
number of ipads sold = b
i sold 4 iphones more than ipad that becomes
a = b+4
then the equation of total commission becomes
30a+20b = 520
substituting a =b+4 in the above equation
30(b+4)+20b = 520
30b+120+20b = 520
50b =520-120
50b = 400
b = 400/50
b=8
number of iphones i sold = a = b+4 = 8+4 = 12
number of ipads i sold = 8
so i sold 12 iphones and 8 ipads to earn the commission of $520</span>
Answer:

Step-by-step explanation:
The shortest distance d, of a point (a, b, c) from a plane mx + ny + tz = r is given by:
--------------------(i)
From the question,
the point is (5, 0, -6)
the plane is x + y + z = 6
Therefore,
a = 5
b = 0
c = -6
m = 1
n = 1
t = 1
r = 6
Substitute these values into equation (i) as follows;




Therefore, the shortest distance from the point to the plane is 
Answer:
The numbers are 1 and 17
Step-by-step explanation:
The only factors of 17 are 1 and 17 since 17 is a prime number
1*17 =17
1+17 =18
N.O = 4
N is midpoint of M.0
Meaning M.N also has to be 4
4+4= 8
N.P = 6
0.P = 2
8+ 2 = 10
Answer: Option C) Raj forgot the negative when substituting -15+9x for y.
Solution:
(1) 9x-y=15
(2) 2x+8y=28
Isolating y in the first equation. Subtracting 9x both sides of the equation:
(1) 9x-y-9x=15-9x
Subtracting:
(1) -y=15-9x
Multiplying both sides of the equation by -1:
(1) (-1)(-y)=(-1)(15-9x)
(1) y=-15+9x
Then Raj found the value of y. It's not option D.
Substitutng y by -15+9x in the second equation:
(2) 2x+8(-15+9x)=28
Then option C) is the answer: Raj forgot the negative when substituting -15+9x for y.
Eliminating the parentheses applying the distributive property in the multiplication:
(2) 2x-120+72x=28
Adding similar terms:
(2) 74x-120=28
Solving for x. Adding 120 both sides of the equation:
(2) 74x-120+120=28+120
Adding:
(2) 74x=148
Dividing both sides of the equation by 74:
(2) 74x/74=148/74
Dividing:
(2) x=2
Solving for y: Replacing x by 2 in the first equation:
(1) y=-15+9x
(1) y=-15+9(2)
Multiplying:
(1) y=-15+18
Subtracting:
(1) y=3