This is the basic and conceptual question from linear equations in two variables in which we have given two equations 2x+3y=7, (a+b)x+(2a-b)y=21 and we have been asked to find the value of a and b for which the given equations has infinite solutions

Kindly give me a detailed solution of this question

RS Aggarwal, Class 10, chapter 3D, question no 25