Answer:
(x, y) = (1, 3)
Explanation:
You want to solve this system of equations by substitution:
- 0.2x +0.3y -1.1 = 0
- 0.7x -0.5y +0.8 = 0
Expression for x
We can solve the first equation for an expression in x:
x = (1.1 -0.3y)/0.2 = (11 -3y)/2
Substitution
Substituting for x in the second equation gives ...
0.7(11 -3y)/2 -0.5y +0.8 = 0
7.7 -2.1y -y +1.6 = 0 . . . . . . . . . multiply by 2, eliminate parentheses
-3.1y +9.3 = 0 . . . . . . . . . . . . collect terms
y -3 = 0 . . . . . . . . . . . . . . . divide by -3.1
y = 3 . . . . . . . . . . . . . . . add 3
x = (11 -3(3))/2 = 2/2 = 1 . . . . . find x
The solution is (x, y) = (1, 3).
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Additional comment
A graphing calculator confirms the solution.