So x + y = 45, and 4x + 5y = 195. Get y by itself. Subtract x from both sides in the first equation to get y = 45 -x, and subtract 4x from the second equation to get 5y = 195 - 4x. Divide by 5 to both sides to get y = 39 - 4/5x. 39 - 4/5x = 45 - x. Add x to both sides to get 39 - 1/5x = 45. Subtract 39 from both sides to get -1/5x = 6. Divide by -1/5 to get x = -30, or 30. In the first equation, do 30 + y = 45. Subtract 30 from both sides to get y = 15. Check. 4(30) + 15(5) = 195, or 120 + 75 = 195.
Answer:
The speed with which Ryan was rowing was 4 mph
Step-by-step explanation:
With a small boat, Ryan wants to row towards an island and come back at a speed of x mph and the island is 20 miles away from him.
Therefore, total 20 + 20 = 40 miles he rowed for 5 hours.
On the way to the island, there was a wind of 4 mph in the direction of his motion and on the way back also there was a wind of 4 mph in the direction of his motion.
So, in the total journey, he has a speed of (x + 4) mph.
Therefore, 
⇒ x + 4 = 8
⇒ x = 4 mph.
Therefore, the speed with which Ryan was rowing was 4 mph. (Answer)
Answer:
Option C (f(x) = 
)
Step-by-step explanation:
In this question, the first step is to write the general form of the quadratic equation, which is f(x) = 
, where a, b, and c are the arbitrary constants. There are certain characteristics of the values of a, b, and c which determine the nature of the function. If a is a positive coefficient (i.e. if a>0), then the quadratic function is a minimizing function. On the other hand, a is negative (i.e. if a<0), then the quadratic function is a maximizing function. Since the latter condition is required, therefore, the first option (f(x) = 
) and the last option (f(x) = 
) are incorrect. The features of the values of b are irrelevant in this question, so that will not be discussed here. The value of c is actually the y-intercept of the quadratic equation. Since the y-intercept is 4, the correct choice for this question will be Option C (f(x) = ). In short, Option C fulfills both the criteria of the function which has a maximum and a y-intercept of 4!!!
Answer:
Step-by-step explanation:
45
