Please solve these coin problems:

1 answer:

6 0

1)
Solving from system of equations:
x- amount of 1 cent stamps
y- amount of 33 cent stamps
$\left \{ {{1*x+33*y=18,40} \atop {x+y=80}} \right.\\x=80-y\\0,01*(80-y)+0,33y=18,40\\0,8-0,01y+0,33y=18,40\\0,32y=18,40-0,8\\0,32y=17,60 /:0,32\\y=55\\x=80-55=25$
2)
x- amount of 20 cent stamops
y-amount of 34 cent stamps
From system of equations:
$\left \{ {{0,2x+0,34y=19,90} \atop {x+y=75}} \right.\\x=75-y\\0,2(75-y)+0,34y=19,90\\ 15-0,2y+0
,34y=19,90\\-0,2y+0,34y=19,90-15\\0,14y=4,90/:0,14\\ y=35\\x=75-35=40$

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JulsSmile [24]

Answer:

$\frac{29}{40}$

Step-by-step explanation:

we know that

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Let

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y----> he number of red marbles

we have

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Studentka2010 [4]

Answer:

D) $(-2,-9)$

Step-by-step explanation:

<u>Vertex Form of a Vertical Parabola:</u>

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Vertex -> $(h,k)$

Axis of Symmetry -> $x=h$

Vertical Scale Factor -> $a$

To turn $f(x)=x^2+4x-5$ into vertex form, we need to complete the square on the right side
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This becomes $9=(x+2)^2$
This means that our function in vertex form is $f(x)=(x+2)^2-9$