Sally pays $50.00 for a meal that costs $38.13. She tells the server to keep the difference as a tip. How much is the tip?

2x minus y equals 6, x plus y equals negative 3

In a two-digit number the units' digit is 7 more than the tens' digit. the number with digits reversed is three times as large as the sum of the original number and the two digits. find the number.

Rhombus adef is inscribed into a triangle abc so that they share angle a and the vertex e lies on the side bc . what is the length of the side of the rhombus if ab=c, and ac=b.