Answer:
y = 12
Explanation:
Consider the triangles in the diagram. Triangle QRS (the smaller one on the left) and Triangle PRO (the whole shape)
These two triangles are similar. It helps to write them separately. See image.
You can use a proportion (two ratios equal to each other) to solve this.
There are two good ways to set up an equation.
EITHER:
bottomLeg/sideLeg=bottomLeg/sideLeg
OR
smallbottom/bigbottom=smallside/bigside
see image.
Either way you set it up the answer comes out the same. Pretty much all the work is the same after you crossmultiply.
Solve 9/y = 12/16
OR 9/12 = y/16
see image.