Someone please help, I know its probably easy but my brain isn't working at the moment :T

Answer/Step-by-step explanation:
A. Tens means groups the units into groups of 10. On the other hand, tenth means one part in ten equal parts written as 1/10. Therefore:
30 tens = 30 x 10 = 300
3 tens = 3 x 10 = 30
3 tenths = 3/10 = 0.3
Thus:
30 tens - 3 tens 3 tenths = 300 - 30.3 = 269.7
----------------------------------------------------------------------------------------------------------
B. 3.4
----------------------------------------------------------------------------------------------------------
C. To find 24 tenths - 1 and 3 tenths, you need to convert the mixed number 1 and 3 tenths into a fraction. 1 and 3 tenths = 1/1 + 3/10. To add these fractions, find a common denominator by multiplying both the numerator and denominator of 1/1 by 10. Thus, 1 and 3 tenths = 10/10 + 3/10 = 13/10. Now you can subtract 24/10 - 13/10 by subtracting the numerators to find the correct answer: 24/10 - 13/10 = 11/10, or 1 and 1 tenth
----------------------------------------------------------------------------------------------------------
D. 6 ones 7 hundredths -2.3
We make a place chart for 6 ones 7 hundredths. We write 0 in the remaining place value.
Hundred tens Ones point tenths hundredths thousandths
0 0 6 . 0 7 0
6 one 7 hundredths is 6.07
Now subtract 2.3 from 6.07
6.07 - 2.3 = 3.77
Answer : 3.77
----------------------------------------------------------------------------------------------------------
E. 8.246 - 5 hundredths is equal to 8.196
5 hundredths in number form is 0.050
8.246
- 0.050
----------------
8.196
In subtracting decimals, line up the decimal points to avoid confusion.
Use 0 as padding so that the decimals will contain the same number of digits after the decimal.
----------------------------------------------------------------------------------------------------------
F. In order to determine the result, we have to know about the notation numbers. In a rational number, every position number has a notation.
So, according to the image, we have to change "5 ones 3 tenths":
5 ones 3 tenths= 5*1+3*0.1=5+0.3=5.3
Then:
=5.3-0.53
=4.77