You can 
put this solution on YOUR website! .
Let the dryer costs x dollars (an unknown value).
Then the washer costs (x-48) dollars, according to the condition.
Now I can write this condition
    dryer + washer = 802
as an equation
    (x-48) + x = 802.
Simplify and solve
    x - 48 + x = 802
    2x = 802 + 48
    2x = 850
     x = 850/2 = 425  dollars.
ANSWER.  The dryer costs 425 dollars.
Solved and explained in all details.
Is everything clear to you ?