Answer:
B. 88.8
Step-by-step explanation:
let x represent class y
(x+71.2)/2=80 multiply each side by 2
x+71.2=160 subtract 71.2 by both sides
x=88.8
or
trial an error
replace x with each of the numbers and see if it plugs in.
example:
(80.5+71.2)/2=80
151.7/2=80
75.85=80?
false. incorrect
another example:
(88.8+71.2)/2=80
160/2=80
80=80?
true. correct
Answer:
D 144 in hope this helps you on your test
Answer:
14 students
Step-by-step explanation:
Given
Let:
read a book
watched TV
So, we have:
-- total



Required
Students that did both (x)
This is calculated using:

So, we have:

This gives:

Open brackets


Collect like terms


<em>Hence, 14 students did both</em>
Answer:
a = 31.7
c = 39.1
Step-by-step explanation:
tan54 = a / 23
a = 23 * tg54
a = 31.7
sin54 = 31.7 / c
c = 31.7 / sin54
c = 39.1
:)