Can someone help me please ?

Two sides of a triangle mesure 20cm and 30cm. what is the measure of the third side

What is the volume of a rectangular prism that is 120 centimeters by 2 meters by 1.5 meters in cubic meters?

Problem melissa is her dad build a walkway in their backyard. the walkway will be 54 feet long and 1.5 feet wide. the local hardware store sells tiles which are 1.5 by 1.5 feet and come in boxes of 12. how many boxes of tiles do they need?