For Isabella:
2x + 4y = 11.60
x represents the price of tacos and y represents the price of drinks
For Lucas:
3x + 1y = 8.40.
This is a systems of equation and can be solved by three methods. I’ll use the substitution method.
y = 8.40 - 3x … plug that into the top equation and solve for..
2x + 4(8.40-3x) = 11.60
.. simplify;
2x + 33.6 - 12x = 11.60
.. combine like terms;
-10x + 33.60 = 11.60
.. solve;
-10x = -19
.. solve;
divide by -10 on both sides of the equation..
-19/-10 = 1.9.. x = 1.9 ; this means that tacos cost $1.90. Let’s plug this into our original equations to figure out the price of each drink.
3(1.9)+y=8.40
.. simplify;
5.7 + y = 8.40
.. solve;
y = $2.70.. this means each drink costs $2.70.
We can work even further to double check our answers by plugging both numbers in the equations. Remember;
y = 2.70 (drinks)
x = 1.90 (tacos)