Explain how you can just look at an equation or an expression and correctly identify which type of change it represents, growth or decay.

Assuming you can graph it out, you would always have a gradient at certain points.
A positive gradient = growth
A negative gradient = decay
If it's in the form y = mx + c (linear), m would be the gradient. Polynomials would need to be differentiated to find the gradient.

3units/ 5 feet = 60 units/ 100 feet3 units/ 5 feet = 18 units/ 30 feetthe dimensions of the scale drawing are 60 units by 18 units.hope this !

Iam unsure about what the proof is, therefore as much as wish to i can not.