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
Step-by-step explanation:
first you find 60% of 357.50 which is $214.50. Next you would add $357.50+214.50=572
so the awnser is
the sale price of a popular smart phone is $572.
Hope this helps!!
Answer: Choice B and D are both correct.
Step-by-step explanation:
The expression has two adjacent negative signs in the middle. The two negative signs are to be multiplied, which then produces one positive sign.
Choice B is therefore correct because the expression becomes 6+6 which is 6 to the right of the number line where the numbers are increasing.
Choice D is also equally correct because the addition of 6 to 6 equals 12(6+6 = 12).
