Answer:
21
Step-by-step explanation:
20 x 10 = 200 so 20 students sleep for 9 hours
that leaves 10
since 10 is half of 20, half of 2 is 1 so that last 10 = 1 student,
making 21 students
Answer:
3
Step-by-step explanation:
Divide
by 

Answer:
11%
Step-by-step explanation:
The full circle graph represents 100% of the given population. All populations are given except for "three or more." Adding all percentages of each population should add up to 100%.
No absences (none): 23%
One absence: 45%
Two absences: 21%
Three more absences: unknown.
Let the variable x represent the unknown population.
23% + 45% + 21% + x = 100%
Combine like terms.
89% + x = 100%
Subtract 89% from both sides.
x = 11%
To put it more simply, subtract all the percentages from 100% to get the percent of the missing population. 100 - 23 - 45 - 21 = 11
I'm assuming that you meant:
y = 7x² + 3
Remember! Inputs are always x values (unless stated otherwise). Meaning the problem says:
x = 4
y = 7(4)² + 3
The square only applies to the 4. The 7 is not going to be squared! (To be exact it only applies to whatever the value of x is.
4² = 4·4 = 16
Remember:
Parenthesis
Exponents
Multiplication
Division
Addition
Subtraction
Follow PEMDAS from left to right (or in the case above from top to bottom).
7·16 + 3 = ?
16·7 = 10·7 + 6·7 = 70 + 42 = 112
(All I did to multiply was break it up into parts. If it confuses you don't worry about it, and just multiply it out like normal or use a calculator if you are allowed to)
112 + 3 = ?
Our output is:
115!
85/100
17/20 when simplified