Hey! Here's some hints:

1) You know the area of a circle is π (r)^2. The radius of the smaller circle is 7 but the radius of the bigger circle is 7+3 (we can imagine that 3 adding on to the length of 7 to meet the outer circle).

Hence the area of the shaded region would be the area of the outer circle - area of the inner circle. Can you solve it now? :)

2) So we have a rectangle and a circle. Finding the area of the rectangle is easy right?

Length x width

But how do we know the radius of the circle? Well, we can see that the width of the rectangle is 50cm, which, if we write 50cm on the left side of the rectangle, happens to be the diameter of the circle. Hence the radius is half of that. Now the area of the shaded region is the (Area of rectangle - area of the semi circle). Can you solve it now? :)

3) If the wire is cut to give 2 circles of the same radius, it means that the 2 circles are identical. Hence, using half the length of the wire for one circle would give a circumference of 18π. Using the circumference formula C = 2πr, we can find the radius, and hence the area.

can you solve these questions now? :)