When the same two digits are next to each other, such as 2.2 you know the relationship is that the 2 in the ones place is exactly 10 x that of the 2 in the tenths place. The same relationship applies that the 2 in the tenths place is exactly 1/10 that of the 2 in the tens place. So the number to the left of the other would be a multiple of that number; the number on the right of the other would be a division of the that number.
The phone costs $930, and he already has $320 saved in his bank account so subtract 320 from 930. You will get 610. Then, you take 610 and divide it by 20 because he earns $20 a week. I hope this helped.
