x-2y=.9 4x-3y=13.1
solving linear systems algebraically using substitution method
Solve the first equation for x in terms of y.
x- 2y = 0.9
x = 2y + 0.9
Substitute the right-hand side of that equation for
the x in the second equation and solve for y.
4x - 3y = 13.1
4(2y + 0.9) - 3y = 13.1
8y + 366 - 3y = 13.1
8y - 3y = 13.1 - 3.6
5y = 9.5
y = 9.5 / 5
y = 1.9
Substitute that for the y in the first
equation and solve for x.
x - 2y = 0.9
x - 2(1.9) = 0.9
x - 3.8 = 0.9
x = 4.7
Use both of those values in the second
equation to check your work.
4x - 3y = 13.1
4(4.7) - 3(1.9) = 13.1
18.8 - 5.7 = 13.1
13.1 = 13.1