Answer: There are 36 cows that can eaten 72 acres of grass in 126 days.
Step-by-step explanation:
Let x be the amount of grass in an acre initially.
Let y be the amount of grass grown in an acre per day.
Since we have given that
12 cows can eat 10 acres of grass in 28 days
12×28 = 10x + 10×28 y
336 = 10x + 280 y----------------------------(1)
Similarly,
21 cows can eat 30 acres of grass in 63 days.
21×63 = 30x + 30×63 y
1323 = 30x +1890 y ---------------------------(2)
So, by graphing method, we get the value of x and y

So, we have, 72 acres of grass in 126 days, we need to find the number of cows.
So, it becomes,
c×126 = 72x + 72×126 y

Hence, there are 36 cows that can eaten 72 acres of grass in 126 days.
I think that Devon swam at least 35 minutes each day for 5 days because if he exercised 225 minutes and each day he walked for 10 minutes then if you divide 225 by 5 you get 45 so every day he exercised 45 minutes and since he walked for 10 minutes you subtract 10 from 45 which gives you 35 so he swam for 35 minutes.
Answer:
Infinite number of solutions.
Step-by-step explanation:
y = -7x - 2
y + 3 = -7x + 1
Subtract 3 from both sides:
y = -7x - 2
- this is the same as the first equation.
We can put any number of valid combinations of x and y into this equation.
So there are infinite solutions.
Answer:
30 blue pins
Step-by-step explanation:
30% is the same as 30 out of 100, so this can be written in this fraction: 
now, you should multiply this fraction by the total number of pins she ordered:
100 x 
to solve this, you can simplify by dividing 100 by 100, this equals 1
30 times 1 is 30
there are 30 blue pins