15% of 80 is 12, so he got $12 in tips
so the total amount of money earned should be $92 dollars
The speed of the current in a river is 6 miles per hour
<em><u>Solution:</u></em>
Given that,
Speed of boat in still water = 20 miles per hour
Time taken = 3 hours
Distance downstream = 78 miles
To find: Speed of current
<em><u>If the speed of a boat in still water is u km/hr and the speed of the stream is v km/hr, then: </u></em>
Speed downstream = (u + v) km/hr
Speed upstream = (u - v) km/hr
<em><u>Therefore, speed downstream is given as:</u></em>

We know that,
Speed downstream = (u + v)
26 = 20 + v
v = 26 - 20
v = 6 miles per hour
Thus speed of the current in a river is 6 miles per hour
That is around 13 or 14 cents. The specific answer is 13.65853659 cents, but you can either round up to 14 or round down to 13 (rounding up to 14 is the correct way to do it.)
First you divide 1.12 by 8.2 to get the unit rate because It takes $1.12 to buy 8.2 ounces. 1.12/8.2=13.65853659
Hope this helped!
She should use a computer to select 30 students at random then ask which ones play chess. The other options could produce more skewed results.