The Two Watches

    4) Suppose a person has sold two different kinds of inexpensive
watches -- one for $20,  and the other for $25.  If he made $7,035
by selling 312 of them,  how many did he sell of each kind of
watch?

        25x + 20(312-x) = 7035

        25x + 6240 -20x = 7035

        5x + 6240 = 7035

        5x = 795

        x = 159

    Since "x" stands for the number of $25 dollar watches, then
it was 159 of those that were sold; and at that price, it will
bring in $3,975.   When we plug the value of x into the term for
the $20 watches, we have 20(312-159), which equals 153 watches;
and at $20 per watch that is $3,060.  So all in all, when double-checking,
it totals 312 watches sold for $7,035.