Answer:
The second option: 3 (6 - 5n)/20n
Step-by-step explanation:
Make sure all fractions have a common denominator:
Step 1. Find a common multiple between all three denominators
5, 4, and 10 all have a common multiple of 20. Proof: 5 × 4 = 20, 4 × 5 = 20, and 10 × 2 = 20
Step 2. Multiply the denominators to get to 20. Whatever you do to the bottom (denominator) must be done to the top (numerator).
1/5n × 4/4 = 4/20n
3/4 × 5n/5n = 15n/20n
7/10n × 2/2 = 14/20n
Your fractions now all have a common denominator of 20n.
Rewrite the equation using the new fractions:
4/20n - 15n/20n + 14/20n
Only focus on adding/subtracting the numerators; the denominators will stay the same: 20n.
(4 - 15n + 14)/20n
Combine like terms:
(18 - 15n)/20n
Factor out any numbers possible:
3(6 - 5n)/20n
Note* 3 go into both 18 and 15, which allows us to factor 3 out. 18 ÷ 3 = 6 and 15 ÷ 3 = 5, giving us our new numbers inside the parentheses.
