Answer:
A.
Step-by-step explanation:
if they are similar then you can set up a proportion to solve.
5/x = 7/4
cross multiple to get 20=7x
x=20/7
Answer:
8.5 miles an hour.
Step-by-step explanation:
There are many ways to do this, but I am going to do it the way I think is the most simple.
First, divide 748 yards by 3 minutes to get the amount of yards per minute. 748 / 3 = 249.33333
Second, divide the previously gotten number (249.33333, [3's go on forever]) by the amount of yards in a mile (which is 1760 yards per mile). This turns into 249.33333 / 1760 = 0.1416666 (6's go on forever). This is miles per minute so you must make it per hour.
You then multiply that infinite number by the amount of minutes in an hour (60 minutes per hour). 0.14166666 * 60 = 8.5 miles per hour.
Lets:
x=number of boys.
y=number of girls
We can suggest this system of equations:
x/y=11/13 ⇒x=11y /13
x=y-72
We can solve this system by substitution method
(11y/13)=y-72
lower common multiple=13
11y=13y-936
11y-13y=-936
-2y=-936
y=-936/-2
y=468
x=11y/13=11(468)/13=396
There are 396 boys and 468 girls in this school,
number of kids=number of boys + number of girls.
number of kids=396+468=864
Answer: there are 864 kids in this school.