we know that
x²+px−35=0-------> has one root that is equal to 7
so
substitute x=7 in the equation
7²+p*7−35=0
49+p*7−35=0
14+p*7=0
p=-14/7------> p=-2
the answer Part a) is
the value of the coefficient p is -2
Part b) Find the other root
x²+px−35=0-----> x²-2x−35=0
using a graph tool-------> to resolve the second order equation
see the attached figure
the other root is
x=-5
the answer part b) is
the value of the other root is -5