Copier N prints at a rate of 104 letters in every 4 minutes and Copier P prints at a rate of 138 letters in every 6 minutes. At 6 p.m., both copiers started printing. After a while, Copier N stopped printing for some time as the ink cartridges were being changed before it continued to print again. Copier P continued printing during this time. At 8 p.m., the total number of letters printed during the past two hours was 7957. Express the number of letters printed by Copier N as a percentage of the total number of letters printed by both copiers. Round off your answer to 2 decimal places.
Number of letters Copier N prints per min = 104 ÷ 4 = 26
Number of letters Copier P prints per min = 138 ÷ 6 = 23

From 6 p.m. to 8 p.m. = 2 h
1 h = 60 min
2 h = 120 min

Number of letters printed by Copier P in 6 h
= 120 x 23
= 2760

Number of letters printed by Copier N in 6 h
= 7957 - 2760
= 5197

Percentage of the number of letters that Copier N printed over the total number of letters printed
= ⁵¹⁹⁷₇₉₅₇ x 100%
≈ 65.31%

Answer(s): 65.31%