Question 56259
Write a simple equation for each statement:
:
The sum of two numbers is 90.
x + y = 90
:
 The second is 10 more than 4 times the first,
y = x + 10

What are the two numbers? 

Since y = x+10 we can substitute it for y in the 1st equation:
x + (x+10) = 90
    2x + 10 = 90
        2x = 90 - 10
         x = 80/2
         x = 40
:
If x = 40 then obviously, y = 50, which is 10 more that x