Question

A restraunt earns $1073 on Friday and $1108 on Saturday. Write and solve an equation to find the amount x (in dollars) the restraunt needs to earn on Sunday to average $100 per day over the three- day period. Write your equation so that the units on each side of the equation are dollars per day.

Answer 1

For this case, the average is the sum of the amounts of the three days divided by three.

We know the earn of Friday and Saturdar. We can assign x to the earn of saturday.

$Promedio= \frac{1073USD + 1108USD + xUSD}{3} =100 USD$

$Promedio= \frac{2181USD + xUSD}{3} =100 USD$

We need to multiply by 3 both sides of the equation.

$3(\frac{2181USD + xUSD}{3}) =3(100 USD)$

2181 USD + x USD =300 USD

We need to substrat 2181 USD in both sides.

2181 USD - 2181 USD + x USD =300 USD - 2181 USD 

x USD =300 USD - 2181 USD 

x USD = - 1881 USD

They need a negative earn in order to have an average earn of 100 USD per day. 

1073 USD + 1108 USD - 1881 USD = 300 USD

300 USD / 3 = 100 USD $[tex]2181 USD - 2181 USD+ xUSD =3100 USD - 2181 USD$[/tex]