Janaya buys a postcard from each travel destination she visits. Before starting her travels this year, Janaya had 20 postcards. During the year, she added 3 more postcards to her collection.

The percentage increase in Jayana's postcard collection is 15%

Step-by-step explanation:

Jayana had 20 postcards last year

With 3 more postcards this year

From the given equation Quantity = Percent x Whole

Here;

Let P = Percent/100%

Quantity = Increment in postcard = 3 postcards

Whole = The total postcards from last year = 20 postcards

Hence,

3 postcards = P x 20 postcards

P = 3/20 = 0.15

Recall P = Percent/100%

∴ Percent = P x 100% = 0.15 x 100% = 15%

The percentage increase in Jayana's postcard collection is 15%