# Question #c6b2b

Jan 7, 2017

The number of calories in a single Big Mac is $540$.

#### Explanation:

We consider the Big Mac as $x$ and the two small fries as $y$. From the data:

$x + y = 1000$
$3 x + y = 2080$

Subtracting the first equation from the second equation, we get:

$\left(3 x + y\right) - \left(x + y\right) = 2080 - 1000$

Open the brackets and simplify. The product of a negative and a positive is a negative.

$3 x + y - x - y = 2080 - 1000$

$2 x = 1080$

Divide both sides by $2$.

$x = 540$