Answer:
84 cm^2
Step-by-step explanation:
The area of a triangle is
A = 1/2 bh where b is the length of the base and h is the height
A = 1/2 ( 5+9) * 12
A = 1/2 (14) * 12
A =84
I don't know about the first one but for the second one:
x=-17,y=3
x+y=-14
x=x
y=x+20
x+(x+20)=-14
2x+20=-14
2x=-14-20
2x=-34
x=-34/2
x=-17
y=-17+20
y=3
