Answer:
30cm3
Step-by-step explanation:
Volume=Base area *height
Base area is a triangle=1/2 *base*height
1/2*3*4=6cm2
Height=5cm
Volume=6*5=30cm3
Sixty square root five (simplified) There ya go hope it helps
Percent decrease { (original number - new number) / original number....x 100
percent decrease : (75 - 25) / 75....x 100
50 / 75...x 100
0.666 x 100
66.6% decrease <==not sure if u need it rounded ?