hi. This is is how it goes tep by step.
Cut the rectangle/shape the way you feel more comfortable. However, you don't know so I will recommend you cut it in half from where the 12 is. so now the 12 ft would be broken in to 2. the top section would be 45 ft because 5 times 9 is 45. the bottom would be 98 because 7 time 14 is 98. the total would be 143. for the first one.