Mis the message you want to send.

The public key is(n, e),n = p*q,143 = 11*13

Cis the coded message and it is coded byC = M^e mod n

C= 48 = 9^7 mod 143, to decode we needdwhich is the inverse ofe

d*e is congruent to 1 mod (#'s relatively prime to n)

d*e is congruent to 1 mod ((p-1)*(q-1)

d*9 is congruent to 1 mod 120

d = 103

We can now decode the coded messageCwhich is 48 by

M = C^d mod n

M = 48^103 mod 143

M = 9

I am not an expert in modular arithmetic so if you want to add something please do. I just joined this forum resently and only saw your post a couple of days ago. I hope you got an answer long before today