Tim has 56 more postcards than Paul.
Step-by-step explanation:
Total postcards boys have = 280
Let,
x = Paul's postcards
y = Shawn's postcards
z = Tim's postcards
According to given statement;
x + y + z = 280 Eqn 1
Eqn 2
Eqn 3
Putting value of y from Eqn 3 in Eqn 2
Eqn 4
Putting value of x and y from Eqn 4 and Eqn 3 in Eqn 1

Multiplying both sides by 

Putting z=120 in Eqn 3

Putting y=96 in Eqn 2

Difference of Tim and Paul = 120-64 = 56
Tim has 56 more postcards than Paul.
Keywords: linear equation, substitution method
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