-1/y = 2/5y. The change from -1 to 2 would be -2, so we now that the change from y to 5y would also have to be -2. -2 = -10 so you multiply by 5. After doing the same to the top you would come to the conclusion that the LCD would be 5y. Hope this helps!
Let us assume that total amount of Nathan's allowance = x
Amount of money deposited by Nathan into his savings account = 7x/9
Remaining amount that Nathan spent = $2.50
Now we have to get to the equation for solving the question asked.
7x/9 + 2.50 = x
7x + (9 * 2.50) = 9x
7x + 22.50 = 9x
22.50 = 9x - 7x
22.50 =2x
x = 22.50/2
= 11.25
So $11.25 is the total allowance of Nathan.
Then The amount of money deposited by
Nathan in savings account = (7/9) * 11.25
= 78.75/9
= 8.75
So Nathan deposits $8.75 in his savings account.
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To round to the nearest tenth, look at the tenths place and then look at the hundredths. If the hundreths is 5 or more, you round up, and if its 4 or less you round down. THE ANSWER IS 6.5