Random, but you are all-knowing: Is there some plausible way for a high-school (11th grade-level) geometry or algerba question to involve the variables 3a and b without being insanely simple?
The 11th grade algebra use of these variables 3a and b that I can think of would be where you teach the student how to solve two equations in two unknowns, like for a simple example:
The larger of two numbers is three times the smaller. Their sum is eight more than twice the smaller. Find the numbers.
Let a represent the smaller number and b represent the larger number.
b = 3a
a + b = 2a + 8
So substitute 3a for b in the second equation:
a + 3a = 2a + 8
So 2a = 8
So a = 4
b = 3a
b = 3 (4)
b = 12