DAY 65

Comment

The value of x + 5y is 25.
When another y is added, the result is 28,
so the value of y is ... .
(The formal equivalent of this is to subtract the 1st equation from the 2nd, and then to substitute the resulting value of y in either equation.)

Answer

y = 3, x = 10.

Readers' methods

Archie Chettle, Carlisle:
x + 6y = 28,
so x + 5y + y = 28,
so 25 + y = 28,
so y = 3.
And if y = 3,
then x + 15 = 25,
so x = 10.

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