Answer:
Rob lunch costs $15 and an equation that can be used to compute it is x = y - 15, where y is the total amount of the bill minus the tip, that is y = 6/0.2
Step-by-step explanation:
In order to solve this question we can attribute a variable to the total amount spent on this lunch, we'll call it "y". The problem states that a 20% tip was given after lunch and that this value was $6. From this information we can calculate the value of "y". We have:
20%*y = 6
(20/100)*y = 6
0.2*y = 6
y = 6/0.2 = $30
Then the problem tells us that Carla's lunch was $15, so we can calculate the value that Rob spent that will be:
x = 30 - 15 = $15
An equation that can be used to find Rob's lunch value is:
x = y - 15
Since we know that y = 6/0.2 we have:
x = 6/0.2 -15 = 30 - 15
