數學 中學 快

23.
1.[30 X (1 + 15%])hours
=(30 X 115%)hours
=(30 X 1.15)hours
=34.5hours

2.[300X(1 + 27%)]seconds
= (300 X 127%)seconds
=(300 X 1.27)seconds
=381seconds

3.$[500 X (1+1000%)]
=$[500 X (1+10)]
=$(500 X 11)
=$5500

4.[123 X (1+200%)]day
=[123 X (1+2)]day
=(123 X 3)day
=369day

5.[60 X (1+45%)]m
=(60 X 145%)m
=(60 X 1.45)m
=87m

6.[350 X (1+33 1/2%)] ml
=(350 X 133.5%)ml
=(350 X 1.335)ml
=467.25ml

24.
1.$[280 X (1-30%)]
=$280 X 70%
=$280 X 0.7
=$196

2.[188 X (1-60%)]kg
=(188 X 40%)kg
=75.2kg

3.[55 X (1-9%)]cm
=(55 X 81%)cm
=(55 X 0.81)cm
=44.55cm

4.[80 X (1-12.5%)]day
=(80 X 87.5%)day
=(80 X 0.875)day
=70day

5.[70 X (1-2.5%)]marks
=(70 X 97.5%)marks
=(70 X 0.975)marks
=68.25marks

6.[3000 X (1-75%)]km
=(3000 X 25%)km
=(3000 X 0.25)km
=750km

全部都係同類題目,自己試試啦!最多俾少少提示你啦!
30 hours increases by 15%
30 x ( 1 + 15% ) 或者 30 + 30 x 15%

$280 decreases by 30%
280 x ( 1 - 30% ) 或者 280 - 280 x 30%