word problem

Question

Katie went to the bakery and bought 6 donuts and 6 coffees it came to 30.55. John went and bought 8 donuts and 4 coffees it came to 28.65. what is the price of 1 large coffee?

Answer 1

6x + 6y = 3055

8x + 4y = 2865

 

elimination method:

 

 24x + 24y = 12220 <--- multiplies first equation by 4

-24x - 12y = -8595   <--- multiplies second equation by -3

 

12y = 3625

 y = 302.083

 

x = [ 3055 - 6y]/6 = 207.083

 

Donut costs $2.07 and the coffee costs $3.02

 

Yes, it checks. There is a penny round-off error, but it checks