Posted by Nadia on Tuesday, November 24, 2009 at 1:24pm.
please solve by method of substitution
0.3x0.4y0.33=0
0.1x + 0.2y .21=0
please give all steps to solve.I think I understand the basic concept but this is little more complicated for me. Thanks in advance

college algebra  MathMate, Tuesday, November 24, 2009 at 3:40pm
Things look a lot easier if you multiply each equation by 100 and simplify, and transpose the constants to the right hand side.
30x  40y = 33 .....(1)
10x + 20y = 21 .....(2)
From equation (2), transpose 20y to the right and divide equation by 10 to get
10x = 21  20y
x = 2.1 2y .... (3)
Substitute x into equation (1) to get
30(2.12y)  40y = 33
63  60y 40y = 33
100y = 3363
100y = 30
y=(30)/(100)
=0.3
Substitute y=0.3 into (3) to get
x=2.12(0.3)
=1.5
Now, substitute these values of x=1.5 and y=0.3 into the original equations to make sure the solution is correct.
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