A teacher asked four of her students to write an expression for the problem below. All products in a store are being discounted
1 answer:
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The correct answer is d.
We have the following system of linear equations:
(I)
(II)
Let's use the elimination method, then let's multiply the equation (1)
and subtracting (I) and (II):
(I)
∴
(I)
(II)
____________________
(III)
∴
We can find the value of x by substituting y either in (I) or (II). Thus, from (I):
∴
∴
∴
∴
Let's substitute the values of x and y into (I) and (2)
(I)
(II)
Finally the answer is:
We have the following system of linear equations:
(I)
(II)
Let's use the elimination method, then let's multiply the equation (1)
(I)
∴
(I)
(II)
____________________
(III)
∴
We can find the value of x by substituting y either in (I) or (II). Thus, from (I):
∴
∴
∴
∴
Let's substitute the values of x and y into (I) and (2)
(I)
(II)
Finally the answer is: