X+y=10, x=10-y
4(10-y)+6y=332
solve the next parts yourself
Substitution is to use one variable to express another variable in order to eliminate one variable in the original equation
When b=0
f(x)=ax^2+c
test each
A. with x^2-1, A is false
B. with -x^2-1, B is false
C. cannot find contradiction
D. the axis is actually x=0, 0 is nithere positive nor negative, false
answer is C
because there are 12 in one layer and there are 3 layers
