Use benchmarks to estimate 12.54 +7.98

Since 12.54 rounds to 12.5, and 7.98 rounds to 8, 12.5 plus 8 would equal 20.5. the estimated answer would be around 20, 20.5 or 21

12.54 ≈ 12.5
7.98 ≈ 8
12.5 + 8 = 20.5
20.5, hope i helped 

The american colonies would have been ruled by a king.