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Answer:
x^2 +4x -21
Step-by-step explanation:
Substitute the given expressions and simplify.
f(x) + g(x)
= (x^2 +3x -28) +(x +7)
= x^2 +(3+1)x +(-28 +7)
= x^2 +4x -21
Answer:
y is also doubled.
Step-by-step explanation:
Direct proportionality between
and
means that

or
,
which indicates a linear relationship between
and
because they are related by a constant.
Therefore, if x is doubled, then the new value of
is 



The new value of
is 2 times the previous; therefore,
is doubled as
is doubled.
Answer:
( D )Each sandwich has 2 pounds of ham.