SOLUTION: On Monday, Harold picked up three donuts and two large coffees for the office staff.He paid $3.94. On Tuesday, Melinda picked up two donuts and six large coffees for the office sta

Algebra ->  Coordinate Systems and Linear Equations  -> Linear Equations and Systems Word Problems -> SOLUTION: On Monday, Harold picked up three donuts and two large coffees for the office staff.He paid $3.94. On Tuesday, Melinda picked up two donuts and six large coffees for the office sta      Log On


   

Question 1019975: On Monday, Harold picked up three donuts and two large coffees for the office staff.He paid $3.94. On Tuesday, Melinda picked up two donuts and six large coffees for the office staff. She paid $7.20. What is the cost of one donut? What is the cost of one large coffee?
The cost of one donut is $
The cost of one large coffee is $
Found 3 solutions by josmiceli, solver91311, lwsshak3:
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Let +a+ = the cost of one donut
Let +b+ = the cost of one large coffee
------------------
(1) +3a+%2B+2b+=+394+
(2) +2a+%2B+6b+=+720+ ( in cents )
------------------------------
Multiply both sides of (1) by +3+ and
subtract (2) from (1)
--------------------
(1) +9a+%2B+6b+=+1182+
(2) +-2a+-+6b+=+-720+
----------------------
+7a+=+462+
+a+=+66+
and
(1) +3a+%2B+2b+=+394+
(1) +3%2A66+%2B+2b+=+394+
(1) +198+%2B+2b+=+394+
(1) +2b+=+196+
(1) +b+=+98+
the cost of one donut is $.66
the cost of one large coffee is $.98
check:
(2) +2a+%2B+6b+=+720+
(2) +a+%2B+3b+=+360+
(2) +66+%2B+3%2A98+=+360+
(2) +66+%2B+294+=+360+
(2) +360+=+360+
OK

Answer by solver91311(24713) About Me  (Show Source):
You can put this solution on YOUR website!





Solve the 2X2 system for , the price of one donut in cents, and , the price of one coffee in cents.

John

My calculator said it, I believe it, that settles it

Answer by lwsshak3(11628) About Me  (Show Source):
You can put this solution on YOUR website!
On Monday, Harold picked up three donuts and two large coffees for the office staff.He paid $3.94. On Tuesday, Melinda picked up two donuts and six large coffees for the office staff. She paid $7.20. What is the cost of one donut? What is the cost of one large coffee?
The cost of one donut is $
The cost of one large coffee is $
let d=cost of one donut
let c=cost of one one lage coffee
3d+2c=3.94
2d+6c=7.20
9d+6c=11.82 (mult.1st eq by3)
2d+6c=7.20
subtract
7d=4.62
d=0.66
2c=3.94-3d=3.94-3*.66=1.96
c=0.98
The cost of one donut is $ 0.66
The cost of one large coffee is $0.98