In the US, people can return to school in their late 20s, 30s, or older to get a higher degree such as a Master or Ph.D. like Rachel, many more are taking training course to (40) their skills
40/40
In the US, people can return to school in their late 20s, 30s, or older to get a higher degree such as a Master or Ph.D. like Rachel, many more are taking training course to (40) ___ their skills.