Simran Bansal

CAT Preparation Community 8y ago

Find x+y if 90/3x-y + 46/2x+3y =7 and 92/2x+3y - 36/3x-y =2 . I tried solving this by substituting a for 1/3x-y and b for 1/2x+3y to form an equation. The equation is 90a+46b=7~(1) and 92b-36a=2~(2). But i cant get it any further by substituting values.The solution just mention that equation (1) is multiplied by 2 and subtracted by (2) to get an equation say (3) . Then we substitute values to get (4) equation multiply equation (3) by 3 and ADD it into (4). But why? why do we multiply it and add/subtract it like that. i dont get the concept. The thing is that it would be easy if i can get a step by step solution and the reason for the steps taken. Thank You.