Question

Given these equations:
x+y=9.0
0.50x+0.20y=3.15
Find the values of x and y.

Answer 1

`x+y=9 \\ 0.5x+0.2y=3.15 \ \ \ |* (-2) \\ \\ x+y=9 \\ \underline{-x-0.4y=-6.3} \\ y-0.4y=9-6.3 \\ 0.6y=2.7 \\ y=(2.7)/(0.6) \\ y=(27)/(6) \\ y=(24)/(6)+(3)/(6) \\ y=4(1)/(2) \\ \\ x+y=9 \\ x+4 (1)/(2)=9 \\ x=9-4(1)/(2) \\ x=4(1)/(2) \\ \\ (x,y)=(4(1)/(2),4(1)/(2))`