Part 1:
A. Like terms must have the same variable and exponent.
B. Give an example of two terms that cannot be combined: 7c and 4b
C. Write one complete sentence to explain why the two terms you wrote cannot be combined: 7c and 4b cannot be combined because they have different variables, and are therefore not like terms.
D. Use distributive property: 2(-4 + 6.1) + 3(5 - x)
2 * -4 = -8
2 * 6.1 = 12.2
-8 + 12.2 + 3(5 - x)
3 * 5 = 15
3 * x = 3x
-8 + 12.2 + 15 -3x
-8 + 12.2 = 4.2
4.2 + 15 = 19.2
19.2 - 3x is the simplest version.
Part 2:
A. Thor is wrong because, in step 4, he subtracted to isolate the variable when he should have divided.
B. 4x + 9 = 6
Step 1: 4x + 9 - 9 = 6 - 9
Step 2: 4x = -3
Step 3: 4x/4 = -3/4
Step 4: x = -0.75