Observe the table,

a.

Write equations that represent the cost of printing digital photos at each lab.

Let be represent the total number of digital photo and be represent the total cost.

The equations represents are

At EZ Online Digital Photos, the total cost is .

At Local Pharmacy, the total cost is .

b. Find the condition at which the cost to print digital photos the same at both stores.

Equate the two total costs.

Find .

                                (Original equation)

    (Subtract from each side)

                                (Apply additive inverse property: )

                                                (Subtract: )

                                           (Divide each side by )

                                                         (Cancel common terms)

Find .

                                               (Substitute )

                                                      (Multiply)

Therefore, the cost will be the same at both stores when photos are taken.

c.

Find a condition when it is best to use EZ Online Digital Photos.

                               (Original equation)

   (Subtract from each side)

                                             (Apply additive inverse property: )

                                           (Divide each side by )

                                                         (Cancel common terms) 

Therefore, EZ Online Digital Photos is best uses for more than digital photos.

The local pharmacy is best uses for fewer than photos.

a.

The equations of EZ Online Digital Photos is and Local Pharmacy is  .

b.

The cost will be the same at both stores when photos are taken.

c.

EZ Online Digital Photos is best uses for more than digital photos.

The local pharmacy is best uses for fewer than photos.