There were 420 birds migrating to the south in the sky this morning. If the ratio of godwits to geese in the sky this morning was 20:40, how many more geese were in the sky?

Total number of birds = 420

Godwits / Geese = 20 : 40 = 20 / 40 = 1 / 2 (40 = 20 * 2, cancel 20 on numerator and denominator)

2 Godwits = 1 Geese by cross multiplying on both sides

Godwits + Geese = 420

substitute in place of geese 2 Godwits

Godwits + 2 Godwits = 420

3 godwits = 420

godwits = 420 / 3 = 140 * 3 / 3 = 140

geese = 2 * godwits = 2 * 140 = 280

We know that the total was 420 birds.

We also know that the ratio of Godwits geese was 20:40, so 2: 4, which after shortening is 1: 2. Now we know that geese is twice the Godwits.

Arrange the relationship:

x + 2x = 420

3x = 420 |:3

x = 140

2x = 2 * 140 = 280

We see that the geese is 280, and 140 Godwits. In total 420.