A China cup and saucer cost 12$. The cup on its own cost 3$ more than the saucer. Form an eqaution for s and solve it. Find the cost of the cup

If the cup = S + 3

and the

saucer = S

then

(S + 3) + S = 12

2s + 3 = 12

2s = 9

s = 4.50

So by itself the saucer costs $4.50. To find the cost of the cup look to the beginning of the problem where we learned that

Cup = S + 3

cup = 4.50 + 3

cup = 7.50

So the saucer is $4.50 and the cup is $7.50 ...

4.50 + 7.50 = $12.00

It checks!