-5-2+7-9 = -9
- and - make a plus :)
What is the question asking for?
Answer: 3
You can find slope by using the 'rise over run' method. Find 2 clear points and count the number of units between those points, across the x axis and up the y axis. You should have 3/1 (y/x) as your slope.
Maria = x
Tom = y
Use substitution
x+y=30
2y=x
2y+y=30
3y=30
y=10
Tom is 10 years old.
x+y=30
x+10=30
x=20
Maria is 20 years old.
