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Halloween Candy

Because of her cute princess costume, a little girl gets 30 more pieces of Halloween candy than her brother in a zombie ninja costume. If together they combine for 190 pieces of candy, how many pieces does the little girl have?

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To solve this using some basic algebra, there are data in the question that can give us two equations.  The fact that sister (s) has 30  more pieces than brother (b) can be written as s = b + 30.  We also know that both together have 190, which would be written as s + b = 190.  Two equations with two unknowns.

These can be solved by substituting the value of s (which is b + 30) in the first equation into the second equation, and then solving for b.  The second equation becomes (b + 30) + b = 190.   Combine like terms, 2b + 30 = 190.  Solving now for b, subtract 30 from both sides to get 2b = 160.  Divide both sides by 2 and you have b = 80 – the number of pieces of candy zombie ninja has!  Since we know that princess has 30 more than him, like in the first equation, we know that sister has 110 pieces of candy.

A simpler approach is to subtract the 30 pieces of candy from the total to get 160.  This removes the difference between them from the total and the remaining amount of 160 can be divided by 2 to get 80.  Adding the 30 back to princess – you know she has 110 pieces of candy.