Answer:
19
Step-by-step explanation:
The pattern is that it +6 every number.
-5 + 6 = 1
1 + 6 = 7
7 + 6 = 13
So the next number is 13 + 6 = 19.
EDIT - I can't add sorry.
X+12=26, x being the amount spent by Richard <span />
Use the slope formula
y sub 2-y sub 1. all over
x sub 2-x sub 1.
so
2+5
-3-1
7/-4
aka -7/4
Put the individuals in the brackets