How do i work this out ?

Question

Solving Algebra Equations

Four numbers are such the the the second number is twice the first number, the third number is 10 less than the second number and the fourth number is a quarter of the third number. Find the value of each of these numbers if their sum is 125. 

Answer 1

Call the numbers a,b,c,d .   b = 2 * a,    c= b -10,  d= c/4,  and a+b+c+d =125.  Put all numbers in equations based on b.    a=  b/2,  b=b  , c= b-10,  d= (b-10)/4.   

 

b/2 + b + (b-10) + (b-10)/4  =125  

 

Combine and solve for b  

 

2.75 * b -12.5  =  125  

 

b=  137.5/2.75   =  550/11 =  50

 

a =55/2  = 25

c=  55 - 10 = 40

 

d =  (50-10)/4  = 10