Question

find the suppplement of the angle 4/5 of 90°

Answer 1

4÷5 × 90
= 72°

supplementary 180° - 72°
108° is answer

Answer 2

ANSWER WITH FULL EXPLANATION

First, let's calculate the given angle. 
$\frac{4}{5}$ of 90° = $(\frac{4}{5}*90)$° = 72°

Now, as we have calculated and found out the measure of the given angle, let's find out the supplement of the given angle. 

Supplement of 72° = (180 - 72)° = 108°

∴ The supplement of the given angle is 108°. 

Congrats ! We have found the answer. 

Hope this may help you. 

If you have any doubt, then you can ask me in the comments.