Let’s make a pair of equations, one for what you ordered, one for what your friend ordered. We’ll have x represent soft tacos and y represent burritos.
Your order: 3x + 3y = 11.25
Your friend’s order: 4x + 2y = 10
The first thing I gather using the information above is that burritos are more expensive then tacos, right? Your order is more expensive, with 1 less taco and 1 more burrito than your friend’s. But now we need to find out just how much more burritos cost.
To do that, pick an equation and simplify it for either x or y. I’ll choose the second equation, because it has a simpler answer. Let’s see what y equals for that one.
2y = 10 - 4x
y = 5 - 2x
Burritos cost 5 minus the cost of two tacos. Just replace y with this in our other equation.
3x + 3(5-2x) = 11.25
Use the distributive property.
3x + 15 - 6x = 11.25
15 - 3x = 11.25
-3x = -3.75
3x = 3.75
One taco costs $1.25
It’s easy to find out what the other variable equals once you have one already. Just pick either of the equations and know how much a taco costs. I’ll jump back to the second one.
4(1.25) + 2y = 10
5 + 2y = 10
2y = 5
y = 2.5
As predicted, burritos cost more. One taco costs $1.25. One burrito costs $2.50. With problems like these, you can always double-check the answers if you’d like. Just plug in the numbers.
My answer is correct, though :)
