30a. A company sells brass and steel machine parts. One shipment contains 3 brass and 10 steel parts and costs $48. A second shipment contains 7 brass and 4 steel parts and costs $54. Find the costs of each type of each type of machine parts.
b. How much would a shipment containing 10 brass and 13 steel machine parts cost?

Question

30a. A company sells brass and steel machine parts. One shipment contains 3 brass and 10 steel parts and costs $48. A second shipment contains 7 brass and 4 steel parts and costs $54. Find the costs of each type of each type of machine parts. 
b. How much would a shipment containing 10 brass and 13 steel machine parts cost?

anonymous · Answer

x=brass y=steel
3x+10y=48
7x+4y=54
multiply first equation by -7 to get -21x-70y=-336
multiply second equation by 3 to get 21x+12y=162
combine
-58y=-174
divide both sides by -58
y=3
put y in for first equation
3x+10(3)=48
3x+30=48
48-30=18
3x=18
divide both sides by 3
x=6

anonymous · Answer

is that a or b?

anonymous · Answer

a.

anonymous · Answer

and since you only want the answer, $99 is b. merry christmas.

anonymous · Answer

i dont want just the answer i want to see how you solved it

anonymous · Answer

well you have the answer, try to work backwards! It'll get you the work you want, better yet,  you'll learn :D

anonymous · Answer

can you just help me start it with the equation?

anonymous · Answer

@jollysailorbold ??

anonymous · Answer

since x=6 and y=3,

10x + 13y = 10(6) + 13(3) = 60 + 39 = 99

The shipment would cost $99.

anonymous · Answer

does that help?

anonymous · Answer

im kind of confused on how that is all  one equation

anonymous · Answer

nevermind i got it THANK YOU SO MUCH! YOU WERE SOO HELPFULL

anonymous · Answer

It's substitution. 

10x + 13y 

you plug things in and get

10(6) + 13(3)

and simplify to get

60 +39

and simplify further to get

$99

anonymous · Answer

oh. haha okay :D pleasure!