The answer is 15 - 5 x
Multiply 5 by 3 ( 15 )
Multiply 5 by -x ( -5x )
I hope this helps and please mark brainliest!
profit=f(x)
so solve for f(x)=1000
1000=70n-400
add 400 to both sides
1400=70n
divide both sides by 70
20=n
20 students need to be enrolled to make a profit of 1000.00