ary and Sharon each buy cupcakes and juice boxes to share with their classmates. Mary buys 15 cupcakes and 8 juice boxes. Sharon buys 10 cupcakes and 8 juice boxes. These equations represent the amounts each of them spends:Mary: 15c+8j=16.45 Sharon: 10c+8j=12.70

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