SOLUTION: Please help me with by solving these systems algebraically they are all 2 variable questions. Thank you 1.){4x+2y=7 y=5x 2.)3c+2d=2 d=4 3.)x+12y=68 x=8y-12 4.)4p+

Algebra ->  Linear-equations -> SOLUTION: Please help me with by solving these systems algebraically they are all 2 variable questions. Thank you 1.){4x+2y=7 y=5x 2.)3c+2d=2 d=4 3.)x+12y=68 x=8y-12 4.)4p+      Log On


   

Question 673978: Please help me with by solving these systems algebraically they are all 2 variable questions. Thank you
1.){4x+2y=7
y=5x
2.)3c+2d=2
d=4
3.)x+12y=68
x=8y-12
4.)4p+2q=8
q=2p+1
5.)x+3y=7
2x-4y=24
Answer by ReadingBoosters(3246) About Me  (Show Source):
You can put this solution on YOUR website!
1)
given y = 5x
substitute into 4x+2y=7 to get
4x + 2(5x) = 7
4x + 10x = 7
14x = 7
x = 7%2F14+=+1%2F7
y = 51%2F7 = 5%2F7
...
2)
given d=4
substitute into 3c+2d=2 to get
3c+2(4)=2
3c + 8 = 2
3c = 2-8
3c = -6
c = -2
...
3)
given x = 8y-12
substitute into x+12y=68 to get
8y-12 + 12y = 68
20y = 68 + 12
20y = 80
y = 4
x = 8(4) - 12 = 32 - 12 = 20
...
4)
given q = 2p+1
substitute into 4p+2q=8 to get
4p + 2(2p+1) = 8
4p + 4p + 2 = 8
8p = 8 - 2
8p = 6
p = 3%2F4
q = %282%29%283%2F4%29+%2B+1+=+3%2F2+%2B+1+=+3%2F2+%2B+2%2F2+=+5%2F2
...
5)
Rearrange x+3y = 7 as x= 7-3y
substitute into 2x-4y=24 to get
2(7-3y) - 4y = 24
14 - 6y - 4y = 24
-10y = 24 - 14
-10y = 10
y = -1
x = 7 - 3(-1) = 7 + 3 = 10
.....................
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