Question

Write an equation and a solution for the problem. A health food store sells oatmeal for $3.60 per pound and bran flakes for $4.80 per pound. How many pounds of each should be used to get a mixture of 30 pounds that sells for $4.00 a pound?

Answer 1

This is what I have so far
3.6x+4.8y=120
and
x+y=30

Answer 2

that's it, now just solve the equations.

Take x+y=30 isolate y, y=30-x

substitute into the other equation and solve

Answer 3

So 3.6x+4.8y30-x=120?

Answer 4

3.6x+4.8(30-x)=120

Answer 5

3.6x+4.8(30-x)=120
3.6x+144+30x=120
33.6x+144=120
Is this good so far?

Answer 6

yes

Answer 7

then i subtract 144 from both sides?

Answer 8

yeah or 120 from both sides

Answer 9

so its 33.6x+24?

Answer 10

wait

Answer 11

-24=33.6x?

Answer 12

oh you know what i just noticed,

This 3.6x+144+30x=120 was supposed to be 3.6x+144-30x=120

so -26.4x-144=120

Answer 13

wait no: -26.4x+144=120

i'm 100% sure this time lol

Answer 14

now what?

Answer 15

subtract 144 from both sides now

Answer 16

to get -24=-26.4

Answer 17

-24=-26.4x

Answer 18

be back in a bit

Answer 19

i'll ask someone else if your not there

Answer 20

theres a mistake somewhere, hold on a second

Answer 21

ok

Answer 22

type it in while im gone and i'll correct it

Answer 23

okay, 3.6x+4.8(30-x)=120

3.6x+144-4.8x=120

144-1.2x=120

-1.2x=120-144=-24

\(x=\dfrac{24}{1.2}\)

Answer 24

Then use the value of x in one of the original equations to find y

Answer 25

Thank You!

Answer 26

no problem !