I hate our education system.

[Harmony Blue]

7. This is a bit too much for a 9th grade student

because most students start to be exposed to Algebra in 9th/10th grade. 8th grade is often where they are taught pre algebra math though so a student if given enough time can figure this out without the aid of Algebra.

But I will say this though...pre algebra skills are probably the most important math skills one can learn. Algebra, Geometry, Pre Calculus, Calculus, Finite mathematics, DE, etc are all important as well. But knowing relative percent differences, absolute percent, ratios, rates, probability, fractions, unit conversions, percent weights, etc are all far more important for science students at college level courses. And this is 7th/8th grade level of math, maybe earlier that is important to know. Even I struggle sometimes to discern the difference between absolute percent and relative percent difference from word problems.