Answer:
84
Step-by-step explanation:
they use 3 plates a day
there are 4 of them
so in one day, they use 12 plates [3x4]
they camp for 7 days, so 12x7.
84!! :D
Answer : 
Given expression is 
To make perfect square trinominal we use completing the square method
In completing the square method we add and subtract the half of square of coefficient of middle term
Here coefficient of middle term is -7
Half of -7 is 
Square of
is
=
So the expression becomes
that gives perfect square trinomial
Hence , the value of 'c' is