Find two numbers whose sum is 90 and one-third of the smaller number is equal to one seventh of the larger number

Answer 1

Let the numbers be x and y, with x the smaller number.
x + y = 90
x/3 = y/7

7x = 3y
x = (3/7) y
Now substitute that x in the first equation.
(10/7)y = 90
y/7 = 9
y = 63
x = 27