Let A = angle, C = complement, S = suplement.

S = 6C ----------(1)

A +C = 90 -------(2)

A +S = 180 ------(3)

(3) minus (2),

S -C = 90 ---------(4)

(4) minus (1),

-C = 90 -6C

-C +6C = 90

5C = 90

C = 90/5 = 18 degrees -----------answer.

Substitute that in (4),

S -18 = 90

S = 90 +18 = 108 degrees -----------answer.

Substitute that in (3),

A +108 = 180

A = 180 -108 = 72 degrees --------answer.