Let u be speed while Lisa drove 240 miles and t be the time in completing 240 miles.
We have been given that Lisa increased her speed 20 mph than initial speed over next 540 miles. So her speed on next 540 miles will be 
mph.
Further more we are given that she took 3 hours more to complete the next 540 miles of the trip than she took in completing initial 240 miles. So she took 
hours in completing next 540 miles.
Since we know 
Now we will substitute our given values in our equation and find out the unknowns. After substitution we will get two equations and two unknowns.
Now we will substitute equation 1 in equation 2
Upon solving this equation, we get
Therefore, total time for Lisa to complete the entire trip is 6+6+3 = 15 hours.
And we know that total distance covered is 240+540 = 780 miles
Hence, average speed
Answer:
one solution
Step-by-step explanation:
* Lets start to solve the question
- The 1st equation x - y = -4
- The 2nd equation 3x + y = 8
- We will use the elimination method to solve this system of equation
∵ x - y = -4 ⇒ (1)
∵ 3x + y = 8 ⇒ (2)
- Add the two equation (1) and (2) to eliminate y
∴ x + 3x = -4 + 8
∴ 4x = 4
- Divide both sides by 4
∴ x = 1
- Substitute the value of x in equation (1) or equation (2) to find
the value of y
- We will use equation (1)
∴ 1 - y = -4
Subtract 1 from both sides
∴ -y = -5
- Divide both sides by -1
∴ y = 5
∴ The solution is (1 , 5)
* The system has one solution
Answer:
cool
Step-by-step explanation:
#21)
<span>Using Pythagorean Theorem a^2 + b^2 = c^2
so
</span>a^2 = c^2 - b^2
x^2 = 42^2 - 38^2
x^2 = 1764 - 1444
x^2 = 320
x =√320
x = √(64 * 5)
x = 8√5
Answer:
-71
Step-by-step explanation:
- 4 x (+1 --5) x (+1 - -5) /6 - (42 - -5)
1 - -5 = 6 and 42 - -5 = 47
-4 x 6 = -24
-24 x 6 = -144
-144 / 6 = -24
-24 - 47 = -71
