What is 3/4 of 16/21? worked out please

How do i do this activity, is appreciated

The volume of gas a balloon can hold varies directly as the cube of its radius. imagine a balloon with a radius of 3 inches can hold 81 cubic inches of gas. how many cubic inches of gas must be released to reduce the radius down to 2 inches?

Write an introductory paragraph for this corrie ten boom and her family were faced with some difficult choices after hitler came to power. some family members paid the ultimate price. write a carefully thought-out paper of at least 200 words dealing with the following concepts: --how should a christian act when evil is in power? --what do you think it would be like to live in an occupied country? remember to proofread anything you write thoroughly.