To add integers with different signs, subtract the lesser absolute value from the greater absolute value. Use the sign of the integer with the greater absolute value for the sum. The following steps will be useful to find the sum of two numbers with different signs.
This is what I got when i graphed it.
Answer:

Step-by-step explanation:
is 7 dollars times the amount of burritos
is 1 dollar times the amount of tacos
because the final price has to be more than the gift card
the money on the gift card
-2=-2y-18
2y=-18+2
2y=-16
Y=-8