Try this:
1) area of f-yard is 60*70=4200 feet²;
2) area of b-yard is 10*30=300 feet², according to condition '<span>on half of his back yard' this area should be 0.5*300=150 feet</span>².
3) total: 4200+150=4350 feet².
It is an arithmetic because it is adding 2 to each number.
All the numbers in this range can be written as

with

and

. Construct a table like so (see attached; apparently the environment for constructing tables isn't supported on this site...)
so that each entry in the table corresponds to the sum of the tens digit (row) and the ones digit (column). Now, you want to find the numbers whose digits add to perfect squares, which occurs when the sum of the digits is either of 1, 4, 9, or 16. You'll notice that this happens along some diagonals.
For each number that occupies an entire diagonal in the table, it's easy to see that that number

shows up

times in the table, so there is one instance of 1, four of 4, and nine of 9. Meanwhile, 16 shows up only twice due to the constraints of the table.
So there are 16 instances of two digit numbers between 10 and 92 whose digits add to perfect squares.
Answer:
8
Step-by-step explanation:
2(5x2-4+2)=2(10-4+2)=2x4=8
Answer:
first answer.. make an induction