4 1/10 in fraction form that is your answer
Assuming those are the legs of the triangle and that you need to find the hypotenuse... I would use the formula: a^2+b^2=c^2
It doesn't matter what a and b are, just fill it in.
25^2+35^2=c^2
625+1225=c^2
1850=c^2
Take the square root of 1850, it isn't a perfect square so I got: 43.01.
If you want, just round it to 43, idc.
So, if I were to check my work, I would need to remember that the hypotenuse is the longest side.
Since 43 is the hypotenuse, it is the longest side.
This is the concept of financial mathematics, the simple interest rate is given by:
S.I.=(PRT)/100
where:
P=principle=$2500
R=rate=5.5%
T=time=1 year
Hence;
S.I.=(5.5*2500.1)/100
=$137.5
Thus the total amount he had after 1 year will be:
2500+137.5
=$2,637.5
Since you have y alone on one side of the equation......
Use substitution and plug in 1/2x-4 for y in the other equation.

Distribute

Combine like terms

Add 8 to both sides

Divide by 4
and 
Plug this value in for x

Simplify

Multiply everything by 8 and simplify

Divide.....

Your answers are:

N+n+2+n+4=54
3n+6=54
3n=48
n=16
16, 18, 20