Eric C. answered 12/10/15
Tutor
5.0
(180)
Engineer, Surfer Dude, Football Player, USC Alum, Math Aficionado
Hey Alex.
Let's set up some variables.
S = number of sundaes sold
B = number of (banana) splits sold
Cs = cost of a sundae ($2)
Cb = cost of a (banana) split ($3)
We know the shop sold 8 more sundaes than banana splits. That means that:
S = B + 8
We know they made a total of 156 in sales. That means that:
Cs*S + Cb*B = 156
2*S + 3*B = 156
So now we have 2 equations and 2 unknowns.
S = B + 8
2S + 3B = 156
Let's substitute.
2(B + 8) + 3B = 156
2B + 16 + 3B = 156
5B = 140
B = 28.
S = 28 + 8 = 36.
There were 36 sundaes and 28 splits sold.
Always a good idea to check your work.
2*36 + 3*28 should equal 156.
72 + 84 = 156. Check.
36 should be 8 more than 28.
36 - 28 = 8. Checkmate.
Hope this helps.