Question

2y-x=0; 10x+15y=105 .

Answer 1

$2y-x=0$ __(1) , $10x+15y=105$ __(2)

multiply equation (1) by 10 and then ad equation (1) and (2)

$-10x+20y=0$

$10x+15y=105$

________________

$35y=105$

$y=\frac{105}{35}$

$y=3$

Now, put $y=3$ in equation (1)

$2\times 3-x=0$

$x=6$