Question

given these equations:

x+y=9.0

0.5x+.2y=3.0

find the values of x and y

Answer 1

I would starb by getting rid of the decimals.
Multiply the second equation by 10

5x + 2y = 30
x + y = 9

multiply the bottom equation by -2

5x + 2y = 30
-2x -2y = -18

Add the two equations to get 3x = 12
so x = 4. Find y by substituting into one of the original equations.

then you should check your answers in both original equations.