For this case, the first thing we must do is define variables.
We have then:
x: cost of tacos
y: cost of enchiladas.
We write the system of equations:
2x + 3y = 7.80
3x + 5y = 12.70
Solving the system we have:
x = 0.9 $
y = 2 $
Answer:
each taco and each enchilada was:
x = 0.9 $
y = 2 $