So the cost of the dryer is d, and let’s call the cost of the washer “d – 43”.
So d + d – 43 = 857, so…
d + d = 900 (we added 43 back onto both sides).
Or, 2d = 900, d = 450. The dryer costs 450.
And if the washer is 43 less, it must have cost 407.
To double check, you add them back together, and sure enough you get 857.
Hope this helps!
Matt in New York