Its 4 by the way cause it is
17) 
18) 
19) 
20) 
Step-by-step explanation:
17) The difference between a number and 8 is 11
Let number = x
then the equation will be:

Solving:


18) Nine less than a number is five.
Let number = x
then the equation will be:

Solving:

19) Seven is equal to a number plus 6
Let number = x
then the equation will be:

Solving:

20) The sum of a number and -4 is -18
Let number = x
then the equation will be:

solving:

Keywords: Algebraic Expressions
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Answer:
If it's a straight line it's linear, if it curves it's non-linear.
Step-by-step explanation:
So for this you just want to divide 4/5 by 9/10 because it is the opposite of the equation.
9/10 / 4/5
To divide fractions, you just multiply and reverse the second fraction.
For example:
9/10 * 5/4
Now you can just normally multiply.
45/40
Or, simplified,
9/8
(Or 1 1/8)
4.02•10^-1
because you move the decimal one space to the left when it's in scientific notation