In this task, we use the ratio. If amount of the discount is $ 79.80, the original price is much higher than the discount. Therefore, arrange the appropriate ratio as below and multiply on the cross:
y --> price (original)
x --> amount of discount
0,21x ----- 79,80$
x ----- y
0,21xy = 79,80x |:x
0,21y=79,80 |:0,21
y=380
The oryginal price is 380$
