just as the problem states, multiply the cost (18.10) by 0.15
18.10 * 0.15 = 2.72
the tip was $2.72
Area of a semi circle = pi * radius^2 / 2
3.14 * 5^2 / 2
3.14 * 25 / 2
78.5 / 2
39.5
Area of a rectangle = length * width
16 * 10
160
Add both of the areas
39.5 + 160
C. 199.5
Descriptions 1, 2, 3, and 5 are accurate, though 5 is ambiguous.
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Description 4 goes with (7x)² = 49x², not 7x².
Description 6 goes with 5·8 + x² + (2x + 8) = x² +2x +48, not 40x² +100x +40.
The description for 5 is accurate, but could also be applied to y² + 3(y - 4), which is why it can be considered to be ambiguous. There are a number of ways to resolve the ambiguity, but they were not used here.
D=vt
So they will travel downstream and upstream the same distance. Downstream they will travel:
d=(2+18)t1
Upstream they will travel:
u=(18-2)t2
Since d=u we can say:
20t1=16t2
We are told the trip lasts 3 hours so t1+t2=3, t2=3-t1, using this in the equation above we have:
20t1=16(3-t1)
20t1=48-16t1
36t1=48
t1=4/3 hours, and from earlier we saw that d=20t1 so:
d=20*4/3
d=80/3 miles
d=26 2/3 miles.
