Question 355108
Let x = # 10 peso bills.  Then 110 - x = # 20 peso bills.
Also{{{10x+20(110-x) = 1560}}},
{{{x + 2(110-x) = 156}}}, after dividing by 10.
{{{x+220-2x=156}}},
{{{-x=-64}}},
{{{x = 64}}}.  So there are 64 10-peso bills, and 46 20-peso bills.