Answer:
16 problems.
Step-by-step explanation:
100% divided by 20 questions.
100/20 is equal to 5, therefore each question is worth 5 points.
Grade of 80% divided by points per question.
80/5 is 16 so the student answered 16 questions correctly.
Answer:
AC = 30
Step-by-step explanation:
Start with:

Combine like terms.

Subtract
from both sides of the equation.

Subtract
from both sides of the equation.

Then, substitute
for
in 

Multiply.

Finally, add.

Answer:
A,C,D
Step-by-step explanation:
Answer:
Step-by-step explanation:

The answer you are looking for is TRUE, the third option. The function of a solution is to prove that the values of the variables are true. Hope this is useful for you