If It is required to find the price of one cupcake and one juice box.
Then solve the equations that represent the amounts each of them spends.
Mary ⇒⇒⇒⇒ 15c + 8j = 16.45 ⇒(1)
Sharon ⇒⇒⇒⇒ 10c + 8j = 12.70 ⇒(2)
solve to find c and j
subtract (2) from (1)
∴ 5 c = 16.45 - 12.7 = 3.75
∴ c = 3.75/5 = 0.75
substituting at (1)
∴ 15 *0.75 + 8j = 16.45
8j = 16.45 - 15*0.75 = 5.2
∴ j = 5.2/8 = 0.65
So, the price of one cupcake = 0.75
and the price of one juice box = 0.65