Question 65600
Solve 
(1)  1/4x - 1/5y = 2
(2)  0.03x - 0.4y = -1.64 

First, we'll convert (1) from fractions to decimals:
 
(1a)  0.25x - 0.2y = 2
(2)   0.03x - 0.4y = -1.64 

Now we could multiply every term in both equations by 100.  That would get rid of the decimals but we really don't need to do that to solve the problem:

Next, multiply (1a) by 2 and we get:

(1b)  0.50x - 0.4y = 4
(2)   0.03x - 0.4y = -1.64 

Now, subtract (2) from (1b) and we have
0.47x =5.64
x=12


Substitute x=12 in (1a) above:

(1)  0.25(12) - 0.2y = 2 simplifying, we have

3-0.2y=2 subtract 3 from both sides
-0.2y=2-3
-0.2y=-1
y=5

CK
Now substitute x=12 and y=5 in (1) above
(1/4)(12)-(1/5)(5)=2
3-1=2
2=2
Substitute in (2)
0.03(12) - 0.4(5) = -1.64 
.36-2=-1.64
-1.64=-1.64

Hope this helps------ptaylor