Question 731512
10 balls and 1 ball bag purchased for $155. 12 balls and 2 ball bags purchased
for $189. How much does 1 ball cost and how much does 1 ball bag cost?
let a = no. of balls
let b = no. of bags
:
"10 balls and 1 ball bag purchased for $155."
10a + b = 155
:
"12 balls and 2 ball bags purchased for $189"
12a + 2b = 189
:
 How much does 1 ball cost and how much does 1 ball bag cost?
:
Multiply the first equation by 2, subtract the 2nd equation
20a + 2b = 310
12a + 2b = 189
------------------subtracting eliminates b, find a
8a = 121
a = 121/8
a = $15.125 for 1 ball.
:
Find the cost of the bag using the 1st original equation
10(15.125) + b = 155
151.25 + b = 155
b = 155 - 151.25
b = $3.75 for 1 bag
:
We expect the solution to be an even cents, check this in the 2nd equation
12(15.125) + 2(3.75) = 
181.50 + 7.50 = 189; checks out with these values