Answer :
Answer:
5 (for c only)
Step-by-step explanation:
for c:
1st cleaning company: [tex]y=17x+15[/tex]
2nd cleaning company: [tex]y=20x[/tex]
set up as a system of equations. for them to cancle out make the y of one equation negative. I'll be making the second one negative ( it doesn't matter though)
it will look like:
[tex]y=17x+15[/tex]
[tex]-y=-20x[/tex]
make the two equations on top of eachother and line the terms up. Then combine them. The variable "y" will cancle out and you'll be left with
[tex]0=-3x+15[/tex]
then you will add 3x to both sides to get [tex]3x=15[/tex] then divide both sides by 3 to get [tex]x=5[/tex]
if you plug in 5 for x into both of the original equations you will see that they will both make $100 in five hours. So you answer is 5