Question

0.2x+0.3y=0.4 0.7x+0.4y=0.1 solve for x and y

Answer 1

0.2x + 0.3y = 0.4
0.7x + 0.4y = 0.1
if you do not want to mess with decimals, you can multiply both equations by 10
you will then get :
2x + 3y = 4 -->(-4)
7x + 4y = 1-->(3)
------------------
-8x - 12y = -16 (result of multiplying by -4)
21x + 12y = 3 (result of multiplying by 3)
-----------------add
13x = -13 -- divide by -13
x = -1
now sub -1 in for x in either equation to find y
2x + 3y = 4
2(-1) + 3y = 4
-2 + 3y = 4
3y = 4 + 2
3y = 6
y = 2
check..
7x + 4y = 1
7(-1) + 4(2) = 1
-7 + 8 = 1
1 = 1 (correct)

x = -1 and y = 2

any questions ?