Find two numbers whose sum is 72 and one of them is twice the other one

Question

system of linear equation question

Answer 1

Classic linear equation problem. Let n1,n2 be two numbers. Then we have eq (1), n1+n2=72, and for eq (2) let n2=2*n1 or 2*n1-n2=0. An easy way to solve is add equations (1) and (2) which gives 3*n1=72. Then n1 = 24 and from eq (2) n2=48. Thus 48+24=72 and 48 is twice 24.