Prize Puzzle Competition 3

7.It is possible to write down the digits 1 to 9 (writing each once and once only, and in order) and then place ordinary arithmetical signs as necessary so that the answer to the entire sum is 100.
For example -
1 x 2 + 34 + 56 + 7 - 8 + 9 = 100
and there several other ways it can be done.
Find a way that uses only + and - signs for addition and subtraction.
Note there are 12 possible answers but only 1 need be given.

8.This brief message has been written in cipher.
Each letter in the original message has been substituted by some other letter.
No letter represents itself.
Can you work out what the original message might have been?

9.Kerry and Nick were going to cut the grass on their square lawn. They agreed that each should cut one-half of the area.
Kerry went first and cut a border 2 metres wide all the way around.
After doing a few sums, Nicki agreed that exactly one-half had been cut and happily cut the rest.
What was the area of the lawn?

The winner of Competition #2 was Matt Chamberlain of Year 10, Reading School
The answers were:

One possible solution,
out of many, is
5.There were 4 possible answers to the complete sum,
but in all of them the value of SOME was 9016
6. Carter used 13 metres more fencing than Martindale.
Martindale's Pythagorean triplet was 9, 40, 41
Carter's was 16, 30, 34
The number of entries was down on those for the previous competition but, for every problem,
nearly all the answers were correct. Well done.