Imagine that Rhianna has 4 blocks. If we mark 3 of those blocks with a different color, then this represents 3/4 of all the blocks.
If we focus on those 3 blocks, and take one-third of them, then we'll pick on 1 block. This is out of the original 4 total. So that's why the answer is1/4
An alternative to see this is to multiply 3/4 and 1/3 (3/4)*(1/3) = (3*1)/(4*3) = 3/12 = 1/4 Getting the same answer as before
If you think about it in a real life scenario, if one person does the job and then another person does the same job at the same speed wouldn't it be the same time? But if its not i think it would be 15 minutes because 45-30 = 15
