A T-shirt supplier charges $12 per T-shirt for the first 50 T-shirts

The trap here is forgetting to account for or to "add back" the first 50

I. Arithmetic
How many T-shirts were there in an order charge of $1500?

Cost 1: $12 per T-shirt for first 50 = $600

Cost 2: $10 per T-shirt, for any number \(x\) T-shirts, AFTER the first 50

T-shirt order total: $1500

(1) 50 T-shirts cost $600
($1500 - $600) = $900 remain

(2) $900 = how many T-shirts?
$900/$10 per shirt = 90 shirts

Number of T-shirts in the order?
50 + 90 = 140

Answer C

II. Algebra
Let \(x\) = # of T-shirts

\((12)(50) + (10)(x-50) = 1500\)
\(600 + 10x - 500 = 1500\)
\(10x + 100 = 1500\)
\(10x = 1400\)
\(x = 140\)

Answer C

We can let n = the total number of shirts and create the equation:

1500 = 12(50) + 10(n - 50)

1500 = 600 + 10n - 500

1400 = 10n

140 = n

Answer: C

Simply make an equation:

12*50 +10*x = 1500 (Total order value)

600 + 10*x = 1500

x = (1500 - 600)/9

x = 90

So, total T shirts = 90 + 50 = 140

Another approach to this problem is by back solving. As always, take a look at the answer choices after reading the prompt and think about what approach makes sense to you e.g. if have strong algebra fundamentals take that route, etc.

I typically start with B then move to D depending on how big or small the choice is compared to what I'm looking for.

Using B, we know the first 50-shirts are $12 a pop (50 shirts at $10 is $500, 50 shirts at $2 is $100; therefore, 50 shirts at $12 is $600). The remaining 75 shirts at $10 is $750. $600 + $750 = $1350 which is too low compared to the $1500 we need. Therefore eliminate B and A (choice A is smaller in value then choice B).

Move to choice D. Same approach as testing choice B and since 100 shirts remain we know that portion costs $1000. Total is $1000 + $600 = $1600, which is way larger in value than the $1500 we're looking for. Therefore, eliminate D and E and select Answer Choice C.

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