Toric lenses.....The sequel!

Hi everyone, it's me again, with a slightly re-worded toric problem.

A thin toric lens is made to the specification:
+7.00DCx135/+9.50DCx45
-3.50DS

1. When a second thin lens of unknown power is placed in contact with the thintoric lens then the resultant power of the two thin lenses is: +2.25DS/-3.75DCx135. What is the power of the unknown second thin lens? Expressyour answer in negative sph-cyl form (6 marks)
   
   I can't quite get my head around what to do! I can't find an example in any of the text books quite like it.
   Any help is, as always greatly appreciated!
   Thanks
   Hannah

Toric lenses.....The sequel!