How do you find out the restrictions on a variable

Pls , the question is in the picture!

The diameter of a circular chip is doubled to use in a new board game. the area of the new chip will be

16. you're planning to buy a boat, a motor, and some miscellaneous boating equipment. the boat costs $325, the motor costs $225, and the equipment costs $79. if you've saved $438 toward these purchases, how much more do you need to save? a. $181 b. $281 c. $291 d. $191