You and a friend buy two fruit smoothies and leave a tip. you split the total and your half comes to $3.60. what percent tip (in decimal form) did you and your friend leave if the fruit smoothies cost $3 each?

Let us first find what the total amount is. It is 3.60 + 3.60 = 7.20
Now let us find the cost of two fruit smoothies. It is 3+3 = 6
So the tip left by you = 7.20 - 6 = 1.20
That is, $1.20 tip for an amount of $7.20
To change it into a percent, form a fraction using the above two numbers and multiply it by 100.
So, the fraction is 1.20/7.20(Numerator 1.20 and denominator 7.20)
Now multiply by 100
1.20/7.20 X 100 = 16.67

21/2 or 5/2