A can type 10 pages in 5 minutes. B can type 5 pages in 10 minutes. Working together, how many pages can they type in 30 minutes?

A can type 10 pages in 5 minutes.
B can type 5 pages in 10 minutes.

Concept Used:
Total Work = Time × Efficiency

Calculation:
A can type 10 pages in 5 minutes.
A can type 1 minute = 10/5 = 2

B can type 5 pages in 10 minutes.
B can type 1 minute = 5/10 = 1/2

Both (A + B)'s type in 1 minutes = 2 + 1/2 = 5/2

The number of pages in 30 minutes = 30 × 5/2 = 75
∴ The number of pages in 30 minutes by both (A + B) is 75.