The number of DVD's sold at Fry's Electronics in a month was 920 and the number of DVD's sold decreased by 12 per month. The number of Blu-ray discs sold at Fry's Electronics in the same month was 502 and the number of Blu-ray discs sold increased by 26 per month. Write a system of equations to model th situation. If this trend continues, in how many months will the number of DVD's sold each month equal the number of Blu-ray discs sold each month? How many each disc is sold in that month?

11 months

788 disc

Step-by-step explanation:

Let

x = number of months

Fry's Electronics;

= 920 - 12x

Blu-ray discs:

= 502 + 26x

Equate both equations

920 - 12x = 502 + 26x

920 - 502 = 26x + 12x

418 = 38x

x = 418/38

x = 11 months

number of months = 11

Substitute 11 into any of the equation

Fry's Electronics;

= 920 - 12x

= 920 - 12(11)

= 920 - 132

= 788 disc sold in that months

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step-by-step explanation:

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hello from mrbilldoesmath!

answer:

(7 x + 6 y) (49 x^2 - 42 x y + 36 y^2)

discussion:

the trick is to recognize that 343 = 7^3 and 216 = 6^3 and, in general,

a^3 + b^3 =   (a + b) (a^2 - a b + b^2).

in our case

343x^3+216y^3   =   (7x)^3 + (6y)^3

so take a = 7x and b = 6y in the above equation to get the answer.

you,

mrb