3x + 4y= -30---(1)
385x - 5y = -30---(2)
equation (1) times 5 on each side---
(3x + 4y)×5=-30×5
15x+20y=-150 ---(3)
equation (2) times 4 on each side---
(385x - 5y)×4 = -30×4
1540x-20y=-120 ---(4)
If u add equation 3 and 4,
(15x+20y)+(1540x-20y)=(-150)+(-120)
1555x=-270
∴x=-270/1555