Answer:
she has 15 boxes of pencils
Step-by-step explanation:
if we have 90 total pencils that need to be split into groups of 6, the way to find how many groups there are is by dividing 90/6, which gives you 15 groups or, in this case, 15 boxes. and you can check your work by multiply the 15 boxes by the 6 pencils in each box, which gives you 90 pencils total, so you're all good!