The fiber type that gives connective tissue great tensile strength is

Collagen fibers

Explanation:

There are three types of fibers:

Collagen fibers: which are in charge of the tensile strength of the connective tissue.

Elastic fibers: Which contain elastin and fibrilin, and are in charge of the elasticity (The capacity to stretch and go back to its normal shape)

Reticular fibers: Which contain Type III Collagen, which is in charge of supporting the network of thin fibers.

69 is the correct math for the amino acids