9514 1404 393
Answer:
- x+y=70; 8.50x+12.50y=10.56(70)
- 36 pounds Antigua
- 34 pounds Rift
Step-by-step explanation:
At the insistence of the problem author, we will let x represent pounds of Antigua coffee and y represent pounds of Rift coffee. Then we have ...
x + y = 70
8.50x +12.50y = 10.56(70) . . . . . total cost of the mix
__
We like to use the variable to represent the high-cost contributor. Here, that is y, so we'll substitute for x:
x = 70-y
8.50(70 -y) +12.50y = 10.56(70)
__
595 +4y = 739.2 . . . . . . . . . . . . . . simplify
4y = 144.2 . . . . . . . . . . . subtract 595
y = 36.05 . . . . . . . divide by 4
x = 70 -36.05 = 33.95
About 36 pounds of Rift Valley coffee and 34 pounds of Gualtemala Antigua coffee must be mixed.
_____
<em>Additional comment</em>
By letting the variable in our equation 8.50(70 -y) +12.50y = 10.56(70) represent the high-cost coffee, we ensure that the simplified equation will have a positive coefficient for the variable. This means we don't have to mess with negative numbers, so eliminating a common source of math errors.
The problem requirement that we use x for the low-cost contributor meant we introduced an extra equation that would not have been needed.
Answer:
The speed of the boat in still water is 13 miles/hour.
The speed of the current is 6 miles/hour.
Step-by-step explanation:
Let the speed of the boat in still water be x
And speed of the current be y
When Irena's travelling downstream, the speed of the boat is:

Traveling down stream the speed of the boat will be :
..(1)
When Irena's travelling upstream, the speed of the boat is:
Time taken by boat = 5 hours and 30 min = 5.5 hours (1 hour = 60 min)

Traveling down stream the peed of the boat will be :
..(2)
On Solving both equation (1)and (2).

putting value of x in (2) equation

y = 6 miles/hour
Putting value of y in (1) equation:
, x = 13 miles/hour
The speed of the boat in still water is 13 miles/hour.
The speed of the current is 6 miles/hour.
Answer:
120
Step-by-step explanation:
multipy 30 by 4 and you should get 120.
You can even do 30+30+30+30 and it will also add up to 120.
Answer:
View Image
Step-by-step explanation:
View Image