The supplement of angle t is 4 times the measure of angle t

Supplementary angles need to equal 180 degrees
 one angle = t
the other angle = 4 x t or 4t
 so we now have t + 4t = 180

4 + 4t = 5t

so we have 5t = 180

divide both sides by 5:
t = 180 /5
t = 36
 so angle t = 36 degrees

the other angle = 4 x 36 = 144 degrees

Ac equals 35 cm long