PLEASE HELP ME WITH ALL OF THESE (WITH AN EXPLANATION FOR BRAINLIEST)

1. -4

2. A

3. y = 1/3x + 3

The area of the larger rectangle has sides of 9cm and 4 cm. We can multiply those sides to find that the area of the larger rectangle is 36cm. 

The area of the smaller rectangle has a side of 3cm and an unknown side. We can find the unknown side: 12cm - 4cm = 8cm. Therefore the are of the smaller rectangle is 8cm*3cm which is 24cm.

We add both of there values to find the total area: 36 + 24 = 60cm