Thank you for your help.
Q1)During a warehouse book sale, Sally spent 62.5% of her money
on 24 books and 18 pens. She also spent 25% of her remaining money
on 18 files. Each pen costs 8/9 as much as the price of one book.
The file costs $7.80 less than a book. Find the total cost of one
book and one pen.
Q2)There are 600 children in Team A and 30% of them are boys. There
are 400 children in Team B and 60% of them are boys. After some
children are transferred from Team B to Team A , 40% of the
children in Team A and 60% of the children in Team B are boys. How
many children are transferred from Team B to Team A?
team A has 3/10 times 600 = 180 boys,
420 girls
team B has 6/10 times 400 = 240 boys,
160 girls
after transfer, team B still have same ratio of boys to girls.
Hence, the number of boys and girls transferred maintain the same
ratio, 3 boys to 2 girls.
after transfer, team A has 180 + 3 units of boys, 420 + 2 units
of girls.
Since new ratio is 40% boys and 60% girls,
3 x team A boys = 2 times team A girls
540 +9 units = 840 + 4 units
5 units = 300
1 unit = 60
hence, total transferred = 5 times 60 = 200 children.