I found this online, hope it helps
Just follow these steps:
Multiply normally, ignoring the decimal points.
Then put the decimal point in the answer - it will have as many decimal places as the two original numbers combined.
add the two equations together
5a+5b=25
-5a+5b=35
------------------
0 + 10b =60
divide by 10
b=6
5a + 5b = 25
5a +5(6) = 25
5a +30 =25
subtract 30 from each side
5a =-5
divide by 5
a = -1
Answer (-1,6)
or a=-1 b=6
Probably the subsitution method
y=1/2x
subsitute that fr y
2x+3(1/2x)=28
2x+3/2x=28
times 2 both sides
4x+3x=56
7x=56
divide by 7 both sides
x=8
sub back
y=1/2x
y=1/2(8)
y=4
(x,y)
(8,4)
You know when it is a periodic function if the values repeats in regular intervals or periods. An example of this is trigonometric functions that repeat over intervals of 2 pi radians.
Well you would have to round this 5 and above goes up. Since 1 is lower than 5 that would leave you at 6.37. 7 rounds up so that would change to 6.4. Lastly 4 would round down, So that would leave you with 6. Now 6 is the simplest form but if your looking for rounded to the nearest tenth the answer would be 6.4. If your looking for rounded to the nearest 100th place 6.37. But over all simplest form is 6.