Please help me, I totally forgot how to calculate this stuff. If you could explain it and put in the set up that would be great

If the perimeter of the garden is 37 ft. the width is x and the length is 15 ft. what is the width of the garden in feet?

Liang bought a basket of apples to make pies for her friends. the basket of apples weighed p pounds. before she had time to make the pies, she ate 3 pounds of apples. there are 17 pounds of apples left to make pies.

The word population in 2013 was about 7.125 billion. in 2003, it was about 6.357billion. which number represents the increase in the world population between 2003 and 2013? a; 0.0768x10/7 b; 0.768x 10/8 c; 7.68x 10/9 d; 7.68x 10/8