Choir boys

Can you work out how many members this choir has from these percentages?

Problem



Two schools share a choir.

Last year there were 30 more students from school B than students from school A in the choir.

This year the number of choir members has increased by 10%.

The number of members from school A has increased by 20%.

The number of members from school B has increased by 5%.

How many members does the choir have this year?

This problem is taken from the UKMT Mathematical Challenges.