Answer:
I. Luke has 81 postcards.
II. Brian has 54 postcards.
Explanation:
Let Luke's collection be L
Let Brian's collection be B
Translating the word problem into an algebraic equation, we have;
L = 27 + B
L + B = 135
Substituting equation 1 into equation 2, we have;
27 + B + B = 135
27 + 2B = 135
2B = 135 - 27
2B = 108
B = 108/2
B = 54
Therefore, Brian has 54 postcards.
To find the value of L;
L = 27 + B
L = 27 + 54
L = 81
Therefore, Luke has 81 postcards
