Question 3562
Let the 2 numbers be x and y

Since sum of two numbers is 42
=> x+y=42...........eq(1)

Since sum of two times a number plus a number is 57
=> 2x+y = 57.....eq(2)

From eq(1)
x = 42 - y

Substituting the value of x in eq(2)
=> 2(42-y) + y = 57
=> 84 -2y + y = 57
=> 84 -y = 57
=> y = 84-57 = 27

So y = 27 and x = 42 - 27 = 15