Janet, Rose, and Tanya buy postcards from their favorite souvenir shop. Janet buys 3 postcards for &1.05. Rose buys 5 postcards for $1.75. Tanya buys 8 postcards for $2.80. Are the cost, y, in dollars and the number of postcards, x, proportional? Explain. Write an equation to represent this relationship.

Step-by-step explanation:

Janet, Rose, and Tanya buy different number postcards from their favorite souvenir shop

Janet buys 3 postcards for $1.05.

This means Janet bought one postcard at the rate of 1.05/3 = 0.35 per postcard.

Rose buys 5 postcards for $1.75.

This means Rose bought one postcard at the rate of 1.75/5 = $0.35 per postcard.

Tanya buys 8 postcards for $2.80.

This means Tanya bought one postcard at the rate of 1.75/5 = $0.35 per postcard.

The unit rate at which Janet, Rose and Tanya bought = $0.35

This means the cost, y, in dollars and the number of postcards, x is proportional.

The equation representing the relationship is

x = 0.35y