30 points! :)





Billie’s monthly cell phone bill includes the cost of cell phone service, 15% tax on the cost of the cell phone service, and a $9.25 data fee. Billie’s monthly cell phone bill totals $61.



What is the cost of the cell phone service before tax is added?



___________$


Sagot :

bill=cost of service+ (15% of cost of service)+data fee
bill=61
data fee=9.25
percent means parts out of 100 so
15%=15/100=0.15
'of' means multiply
c=cost
tax=0.15 times c or 0.15c

61=1c+0.15c+9.25
add like terms
61=1.15c+9.25
subtract 9.25 from both sides
51.75=1.15c
divide both sides by 1.15
45=c

the cost of the phone bill is $45