Answer:
Add
Step-by-step explanation:
10.65*40=426
426+50=476
Based on the calculations, the unknown number is equal to 
- Let the unknown number be x.
<h3>How to find an
unknown number:</h3>
Translate the word problem into an algebraic expression, we have;
Adding 21 to the unknown number:

Multiplying the result by 3:

84 more than two-thirds of the unknown number:

Equating the equations, we have:

Cross-multiplying, we have:

Read more on word problems here: brainly.com/question/13170908
Answer:
30 hours is the right answer
One is significantly fatter than the other and has more friction
12 sas equals 40 over 200-30= x minus 2