Simultaneous Equations Problems

1) In our household, there are twice as many cats as humans, with sixty legs in total. How many cats are there to be fed?

2) A group of 20 people pay a total of $20 to see an exhibition. The admission price is $3 for men, $2 for women and 50c for children. How many men, women and children are there in the group?

3) The sides of a rectangle, in metres, are each a whole number, less than 10.The area of the rectangle is the same value (in m2) as the perimeter (in m). Is this possible? Show with working.https://nzmaths.co.nz/resource/tricky-rectangles