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a 20 pound platter of cookies costs $77. the platter is a mix of peanut butter that costs $4 per pound, sugar that costs $3 per pound, and chocolate chip that’s costs $4.50 per pound. there are two more pounds of sugar cookies than peanut butter. how many pounds of sugar cookies are on the platter?

Respuesta :

GMillar

Answer: 7 pounds of sugar cookies

X+Y+Z = 20

4x + 3y +4.50z = 77

-x + y + 0z = 2

X+Y+Z = 20                      4x + 3y + 4.50z = 77

-x + y +Oz = 2                   (-x + y + 0z = 2) x 4     (-4x +4y+0z=8)

Add the problems vertically

0x + 2y + z = 22              0x +7y + 4.50 z = 85

Rewrite the problem

2y + z = 22                (Times 7)

7y + 4.50 = 85          (Times -2)

14y +7z = 154

-14y - 9z = -170      

Add Vertically

-2z = -16

divide by -2

z = 8

there are 8 Chocy Chips

if we plug 8 for z in 2y + z = 22      we get y = 7

making 5 be X (Cause X+Y+z = 20)

8 Chocy

7 Sugar

5 Peanut butter

-- Gage Millar, Alg 1/2 tutor

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