Here is a model I have made (I'm not a great artist). There are 42 circles in total, placed in 7 columns. Each column has 6 circles. This model represents 42/7 by splitting 42 into 7 parts, which are the columns, and showing that each column has 6 circles, which is the answer to 42/7.
Answer:
Should be 39 years.
there is 12 inches in a foot. and if the tree grows 4 inches every year, then in 3 years the tree would be 1 foot. 13 x 3 = 39, thus proving that in 39 years, it will be 13 feet tall. I may be wrong but this sounds correct.
5x+y=-3 is the standard form