No.137 Increase and Decrease
Example
A middle school had 800 students last year. This year, the number of boys increased by 10% and the number of girls decreased by 5%, making 820 students in total. Find the number of boys and girls this year.
POINT
Represent last year’s numbers with variables, then express this year’s numbers using the percentage increases or decreases.
This year: 440 boys and 380 girls
TRY
TRY 1
A school had 600 students last year. This year, the number of boys increased by 10% and the number of girls decreased by 10%, making 612 students in total. Find the number of boys and girls this year.
396 boys and 216 girls
TRY 2
A school had 500 students last year. This year, the number of boys increased by 20% and the number of girls decreased by 10%, making 540 students in total. Find the number of boys and girls this year.
360 boys and 180 girls