Question

The manager at a restaurant keeps track of the number of calzones and slices sold each day and the total money received. On Wednesday, a total of 86 calzones and slices were sold, and the money collected was $770 . If calzones are sold for $10 and slices are sold for $7 , how many calzones and slices were sold?

Answer 1

c=number of calzones sold
s=number of slices sold


c+s=86
10c+7s=770

alright
subsitute

c+s=86
minus s both sides
c=86-s
subsittute 86-s for c

10c+7s=770
10(86-s)+7s=770
860-10s+7s=770
860-3s=770
minus 860 both sides
-3s=-90
divide both sides by -3
s=30

subsitute back
c=86-s
c=86-30
c=56


56 calzones were sold
30 slices were sold