Part 27
we have the expression
a-4b
For a=7 and b=2
Substitute the value of and the value of b in the expression
so
7-4*(2)=7-8=-1
the answer part 27 is -1
Part 28
we have
For w=-2, x=-3 and y=1
substitute the given values in the expression
the answer part 28 is -2