I'd guess 4/5 because 5 - 1 = 4. That's assuming that the chocolate is the remainder.
It should be 12cm because
h=height
a=area
b=base
h=a/b we have base 15cm and height 8cm
8cm=a/15cm
8cm*15cm=a
120cm^2=a
we then use the area to find the height with base 10
h=a/b
h=120cm^2/10cm
h=12cm
4 - 3y = 31
Subtract 4 from both sides.
-3y = 31 - 4
Simplify.
-3y = 27
Divide both sides by -3.
y = 27/-3
Simplify.
y = -9
~Hope I helped!~
