Courtney has a total of 88 stamps worth $15.56. Some are 25 cent stamps and some 2 cent stamps. How many of each does she have

88 stamps -------------------- >  $15.56
A------------------------------>number of  stamps ------------ >25 cent
B----------------------------- > number of  stamps ------------ >2 cent

A+B=88------------------ > A=88-B
0.25A+.02B=15.56
resolving
0.25(88-B)+0.02B=15.56
22-0.25B+0.02B=15.56
-0.23B=-6.44----------------------- > B=28 stamps of 2 cent
A=88-B-- >88-28=60------------- > A=60 stamps of 25 cent