Q2. (8 pts, Solving Congruences) Let
a,b,d, and
n>1be arbitrary integers. 2.a. Prove that if
ad-=bd(modn), then
a-=b(mod(n)/(gcd(d,n))). 2.b. Solve
7x-=12(mod13)for
xin{0,1,2,dots,12}. 2.c. Solve
84x-38-=79(mod15)for
xin{0,1,2,dots,14}. 2.d. Solve
2x-=3(mod14)for
xin{0,1,2,dots,13}.
