Question 145494
The sum of two numbers is 89.
x + y = 89
x = (89-y)
:
 Adding four times the first number to the second number gives 155.
4x + y = 155
:
y = 155 - 4x; is one of the possible equations
:
:
To solve it, substitute (89-y) for x:
y = 155 - 4(89-y)
:
y = 155 - 356 + 4y
:
y - 4y = -201
:
-3y = -201
y = {{{(-201)/(-3)}}}
y = +67; and  x = (89-67) = 22