Robbie read 229 pages of a storybook over 3 days. On Day 1, he read some pages. On Day 2, he read 90 pages more than he did on Day 1. On Day 3, he read 10% less pages than on Day 2. How many pages did Robbie read on Day 1?
+189 Let p represent the number of pages Robbie read on Day 1.
Since we do not yet know how many pages Robbie read on Day 1, I will represent that as the following:
Day 1: \(p\) pages
Since Robbie read 90 more pages than Day 1, that can be represented mathematically as follows:
Day 2: \(p + 90\) pages
If Robbie read 10% fewer pages than on Day 2, then Robbie effectively read 90% of the number of pages on Day 2.
Day 3: \(\frac{9}{10}\left(p + 90\right) = \frac{9}{10}p + 81\) pages
We know that Robbie read 229 pages in total over the course of 3 days, so we can create and solve an equation of this situation.
\(p + \left(p + 90\right) + \left(\frac{9}{10}p + 81\right) = 229 \\ 2p + \frac{9}{10}p+ 171 = 229 \\ \frac{29}{10}p = 58 \\ p = 20\)
In other words, Robbie read 20 pages on Day 1.
