Working out the unknown number

This task is about using number properties to work out the unknown number.

 

Show how to find the unknown number (represented by a letter) in each of the following equations.

a) 544 + x – 544 = 238 – 238 + 112

  
  
x = _____ 
 
b) 256 + r = 19 + 172 + 256 – 172

 
 
r = _____ 
 
c) 358 + 13 – 13 + m = 179 + 358 – 179

 
  
m = _____ 
 
d) y + 55 = 678 + 54

  
 
y = _____ 
 
e) 88 + 47 = 86 + 46 + t

  
 
t = _____ 
 
f) 65 – q = 66 – 18

  
 
q = _____