So... hmmm if you check the first picture below, for 2)
we could use the proportions of those small, medium and large similar triangles like

now.. for 3) will be the second picture below
To eliminate a cariable in a system of equations, we multiply the variable by a factor that will make both coefficients of the variable to be equal.
Thus, we multiply the coefficient of y in the second equation by a factor that will make it equal to the coefficient of y in the first equation. i.e. multiply 1/2 by a factor that makes it equal to 3/4. and the factor is 3/2.
Therefore, the third option is the correct answer.
1 and 3 I believe sorry if it’s incorrect