Total cost = cost of paper clips + cost of index cards
Total cost = cost of one box of paper clips number of boxes + cost of one box of index cards number of boxes
\(55.40=15p+7i \\ 61.70=12p+10i \\ \\ 61.70-12p=10i \\ i = \frac{61.70-12p}{10} \\ i=6.17- \frac{6p}{5} \\\\ 55.40=15p+7(6.17- \frac{6p}{5})\\55.40=15p+43.19-\frac{42p}{5}\\55.40=15p-8.4p+43.19\\12.21=6.6p\\p=1.85 \\\\55.40=15(1.85) +7i\\55.40=27.75+7i\\7i=27.65\\i=3.95\)
So your answers are:
p = $1.85
i = $3.95
