To solve the system of equations
[tex]\begin{gathered} 0.2x+0.7y=2.2 \\ 0.9x-0.2y=3.2 \end{gathered}[/tex]we need to make the coefficients of one of the variables opposite, that is, they need to have the same value with different sign; let's do this with the y variable, so let's multiply the second equation by 0.7 and the first equation by 0.2; then we have:
[tex]\begin{gathered} 0.04x+0.14y=0.44 \\ 0.63x-0.14y=2.24 \end{gathered}[/tex]Now we add the equations and solve the resulting equation for x:
[tex]\begin{gathered} 0.04x+0.14y+0.63x-0.14y=0.44+2.24 \\ 1.64x=2.68 \\ x=\frac{2.68}{0.67} \\ x=4 \end{gathered}[/tex]Now that we have the value of x we plug it in one of the original equations and solve for y:
[tex]\begin{gathered} 0.2(4)+0.7y=2.2 \\ 0.8+0.7y=2.2 \\ 0.7y=2.2-0.8 \\ 0.7y=1.4 \\ y=\frac{1.4}{0.7} \\ y=2 \end{gathered}[/tex]Therefore, the solution of the system of equation is (4,2)
